QUANTITATIVE REASONING · ALGEBRA FOUNDATIONS

Model the move.
Audit the result.

Build exact algebraic habits across expressions, equations, inequalities, powers, distance, and proportional models—then retrieve them without the chapter label.

5guided lessons
15retrieval prompts
20practice questions
5choices per item

The algebra audit

Model. Transform. Verify. Decide.

  1. 01Model

    Name the variable, relation, unit, grouping, and permitted domain.

  2. 02Transform

    Choose a valid symbolic move and state what it preserves or reverses.

  3. 03Verify

    Substitute, test a region, or check sign, scale, base, and units.

  4. 04Decide

    Return the requested expression, value, set, comparison, percent, or rate.

The five lesson labels follow the official Algebra scope. DAT TRAIN’s sequence, examples, and questions are original study tools and do not imply unpublished topic weights.

Five connected topic lessons

Keep a ledger for every claim.

Each model exposes the exact relation, transformation, boundary, comparison base, or unit that makes the conclusion valid.

01

LESSON 1 · 14 MIN

QR-MAT-EQU-01QR-MAT-EQU-02

Equations and expressions

Translate expressions, solve linear equations, and verify candidates while preserving grouping, signs, and restrictions.

ESSENTIAL QUESTIONWhich transformations preserve the original relationship—and how can substitution prove it?
Semantic equation ledgerEvery row preserves equality.
Equation transformation and verification ledger
LineOperation on both sidesResultInvariant check
StartRead the original relation3x − 5 = 16Equality is the constraint
Isolate termAdd 53x = 21Both sides increased equally
Isolate xDivide by 3x = 7Nonzero divisor preserves equality
Original checkSubstitute x = 721 − 5 = 1616 = 16
SEMANTIC MATH MODEL · COMPLETE TEXT AND TABLE EQUIVALENT INCLUDED
01

Translate the relationship

Build noun phrases and relational phrases before following the surface order of the words.

  • ‘Less than’ reverses the written order.
  • A fraction bar groups its entire numerator and denominator.
02

Preserve equivalence

Apply an invertible operation to both sides and record any restriction introduced by a conditional move.

  • Name the operation before performing it.
  • Do not cancel terms across addition.
03

Verify in the original

Substitute the candidate into the original equation rather than a transformed line.

  • Compare both sides exactly.
  • Reject excluded values and extraneous candidates.

Worked example

Solve 5(x − 2) + 3 = 18 and verify the result.

  1. 1

    Expand or first subtract 3: 5(x − 2) = 15.

  2. 2

    Divide by 5: x − 2 = 3, so x = 5.

  3. 3

    Original check: 5(5 − 2) + 3 = 15 + 3 = 18.

Conclusionx = 5 is the unique solution because the reversible steps preserve equality and the original check succeeds.

Calculator decision ledger

Model mentally
Translate and isolate symbolically.
Estimate
Predict sign and approximate magnitude.
Calculator
Use only for cumbersome arithmetic.
Audit
Substitute into the original equation.

Close the notes first

Retrieve the model.

01Translate ‘four more than three times y.’
3y + 4

‘Three times y’ is the base quantity; four is added to it.

02Solve 4x + 7 = 31.
x = 6

Subtract 7, divide by 4, then verify 24 + 7 = 31.

03Why check a candidate in the original equation?
Conditional transformations can create or retain invalid candidates.

The original relation is the actual acceptance condition.

02

LESSON 2 · 14 MIN

QR-MAT-INE-01QR-MAT-INE-02

Inequalities

Solve linear, compound, and absolute-value inequalities and express the complete region with correct direction and endpoints.

ESSENTIAL QUESTIONWhen does an algebraic move change order, and what does the resulting region include?
Semantic inequality modelDirection, boundary, and region stay explicit.

Text equivalent: The boundary is negative three and is excluded. Every number less than negative three is included; every number greater than or equal to negative three is excluded.

Open boundary at −3; solution extends left
Inequality transformation and endpoint ledger
PassStatementReason
Subtract−3x > 9Adding the same value preserves order
Dividex < −3Division by −3 reverses order
EndpointOpen at −3The inequality is strict
Region testx = −4 works14 > 11 in the original inequality
SEMANTIC MATH MODEL · COMPLETE TEXT AND TABLE EQUIVALENT INCLUDED
01

Protect direction

Adding preserves order; multiplying or dividing by a negative reverses it.

  • Record the sign of the divisor.
  • Reverse once—not once per negative term.
02

Classify endpoints

Strict inequalities exclude a boundary; inclusive inequalities include it.

  • Open means excluded.
  • Closed means included.
03

Combine regions

An ‘and’ condition requires intersection; an ‘or’ condition permits union.

  • Test a point in each region.
  • State the whole set, not one example.

Worked example

Solve −3x + 2 > 11 and describe the number line.

  1. 1

    Subtract 2: −3x > 9.

  2. 2

    Divide by −3 and reverse the sign: x < −3.

  3. 3

    Use an open endpoint at −3 and include all values to its left.

ConclusionThe solution is x < −3, or (−∞, −3); −3 itself is excluded.

Calculator decision ledger

Model mentally
Mark direction, endpoint type, and set operation.
Estimate
Test one value on each side of a boundary.
Calculator
Usually unnecessary for foundational coefficients.
Audit
Verify a boundary and representative region value.

Close the notes first

Retrieve the model.

01What happens to < after division by −5?
It reverses to >.

Multiplication or division by a negative reverses order.

02Write −2 ≤ x < 4 in interval notation.
[−2, 4)

The left endpoint is included; the right endpoint is excluded.

03What set operation usually matches ‘and’?
Intersection

A value must satisfy both conditions simultaneously.

03

LESSON 3 · 12 MIN

QR-MAT-EXP-01

Exponential notation

Apply exponent and scientific-notation rules without losing the base, grouping, reciprocal, or order of magnitude.

ESSENTIAL QUESTIONWhat exactly is the base, and what does the exponent act on?
Exponent and magnitude ledgerName the base before applying a rule.
Exponent structure, exact value, and magnitude checks
ExpressionStructureExact resultMagnitude audit
2⁻³Negative exponent1/8Positive and below 1
3² · 3⁻⁵Same-base product3⁻³ = 1/27Positive and below 1
0.00045Decimal moved 4 places right4.5 × 10⁻⁴Coefficient is in [1, 10)
(−2)⁴ versus −2⁴Grouped versus ungrouped sign16 versus −16Parentheses change the base
SEMANTIC MATH MODEL · COMPLETE TEXT AND TABLE EQUIVALENT INCLUDED
01

Name the base

Parentheses determine whether a sign or product belongs to the powered quantity.

  • (−2)⁴ and −2⁴ differ.
  • An exponent applies before an ungrouped leading sign.
02

Combine only like bases

Products of equal bases add exponents; powers of powers multiply exponents.

  • Do not combine exponents across addition.
  • Keep the reciprocal exact.
03

Audit magnitude

Scientific notation uses a coefficient with absolute value from 1 up to, but not including, 10.

  • Small positive decimals use negative exponents.
  • Move and exponent must offset each other.

Worked example

Simplify (2³ · 2⁻⁵) and estimate its size.

  1. 1

    The bases match, so add exponents: 3 + (−5) = −2.

  2. 2

    Rewrite 2⁻² as the reciprocal 1/2².

  3. 3

    Evaluate exactly: 1/4, which is positive and less than 1 as expected.

ConclusionThe exact value is 1/4; the negative exponent creates a reciprocal, not a negative result.

Calculator decision ledger

Model mentally
Identify base and exponent operation.
Estimate
Predict sign and whether magnitude is above or below 1.
Calculator
Confirm a decimal only after exact simplification.
Audit
Check coefficient range and decimal direction.

Close the notes first

Retrieve the model.

01Rewrite 5⁻² without a negative exponent.
1/25

A negative exponent takes the reciprocal of the positive power.

02Simplify a⁴a⁻¹ for a ≠ 0.
a³

Equal bases in a product add exponents.

03Write 0.0062 in scientific notation.
6.2 × 10⁻³

The decimal moves three places right, so the power of ten is −3.

04

LESSON 4 · 12 MIN

QR-MAT-ABS-01

Absolute value

Interpret absolute value as distance, generate all valid cases, and reject impossible negative-distance claims.

ESSENTIAL QUESTIONWhich points are the stated distance from the reference point?
Absolute-value distance modelTwo directions can share one distance.

Text equivalent: The two solution points are negative two and eight. Their midpoint is three, and each is five units from three.

Two solutions symmetric around x = 3
Absolute-value case and substitution ledger
CaseEquationCandidateOriginal check
Positive direction2x − 6 = 10x = 8|16 − 6| = 10
Negative direction2x − 6 = −10x = −2|−4 − 6| = 10
Feasibility|u| = −2NoneDistance cannot be negative
SEMANTIC MATH MODEL · COMPLETE TEXT AND TABLE EQUIVALENT INCLUDED
01

Read distance

|x − c| measures the distance from x to c on the number line.

  • Distance is never negative.
  • The reference point is c, not −c.
02

Build cases

A positive target distance generates a point on each side of the center.

  • Solve the positive case.
  • Solve the negative case.
03

Check symmetry

Valid solutions lie equally far from the center unless a surrounding restriction removes one.

  • Count all candidates.
  • Test each in the original bars.

Worked example

Solve |2x − 6| = 10.

  1. 1

    Set 2x − 6 = 10, giving x = 8.

  2. 2

    Set 2x − 6 = −10, giving x = −2.

  3. 3

    Check: both inside values have magnitude 10.

ConclusionThe solution set is {−2, 8}; keeping only one case loses half the distance model.

Calculator decision ledger

Model mentally
Identify center and target distance.
Estimate
Predict two symmetric cases, one case, or none.
Calculator
Use only if case arithmetic is cumbersome.
Audit
Substitute every candidate into the original bars.

Close the notes first

Retrieve the model.

01What is |−9|?
9

−9 is nine units from zero.

02Solve |x| = 3.
x = −3 or x = 3

Both points are three units from zero.

03Can |u| = −1 have a real solution?
No

A distance cannot be negative.

05

LESSON 5 · 14 MIN

QR-MAT-RAT-01QR-MAT-RAT-02

Ratios and proportions

Align comparison bases and units, then distinguish direct, inverse, percent-change, and unit-rate models.

ESSENTIAL QUESTIONWhich ratio or product must stay invariant as the quantities change?
Ratio and unit ledgerChoose the invariant before the arithmetic.
Proportion type, invariant, unit, and direction ledger
ModelInvariantUnit resultDirection check
Direct proportionEqual ordered ratiosSame numerator unitBoth quantities scale together
Inverse work modelWorkers × daysDaysMore workers, fewer days
Percent changeChange ÷ originalPercentSign matches increase or decrease
Unit rateQuantity ÷ elapsed unitMiles per hourScale returns 180 miles in 3 hours
SEMANTIC MATH MODEL · COMPLETE TEXT AND TABLE EQUIVALENT INCLUDED
01

Align the base

A ratio is ordered; both sides of a comparison must describe the same quantities in the same units.

  • Label numerator and denominator.
  • Convert units before comparing.
02

Choose direction

Direct proportionality keeps a ratio constant; inverse proportionality keeps a product constant.

  • Ask whether outputs should rise or fall together.
  • Use the verbal relationship, not a keyword alone.
03

Audit scale

Percent change ordinarily uses the original value, while a unit rate divides by one unit of the denominator.

  • Name the comparison base.
  • Attach the resulting unit.

Worked example

Six workers need 10 days. At the same rate, how many days would 15 workers need?

  1. 1

    More workers should require fewer days, so use an inverse model.

  2. 2

    Preserve worker-days: 6 workers × 10 days = 15 workers × d days.

  3. 3

    Solve d = 60/15 = 4 and check that the direction is reasonable.

ConclusionFifteen workers need 4 days under the stated equal-rate assumption.

Calculator decision ledger

Model mentally
Label quantities, units, and direct or inverse direction.
Estimate
Predict whether the answer grows or shrinks.
Calculator
Perform the final division when useful.
Audit
Check units, comparison base, and direction of change.

Close the notes first

Retrieve the model.

01Solve 3/5 = x/20.
x = 12

The denominator scales by four, so the numerator does too.

02What base is used for ordinary percent increase?
The original value

Change is compared with the starting quantity.

03What stays constant in a simple inverse proportion?
The product of the paired quantities

One quantity decreases in the same factor that the other increases.

Randomized retrieval bank

Now solve without the lesson label.

All eight objectives appear in the bank. Every question and all five choices shuffle while each answer remains attached to its independently recomputed key.

20 PRACTICE QUESTIONS

Retrieve before you review.

Question order and all five answer options are shuffled when you begin. The correct answer stays attached to the same underlying choice.

Scope and score notice

Use results for study guidance.

The ADA names these Algebra topics but does not publish their individual question quotas. DAT TRAIN does not invent them.

These original questions are draft and uncalibrated. Accuracy can direct review; it cannot predict an official DAT score.