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Lesson 9~30 minUnit 2 · Patterns & Algebra+90 XP

Expanding and Simplifying

$2(x+3) + 4(x-1)$. Expand both brackets, then collect like terms. Two skills in one problem — this is where algebra gets real.

Today's hook: $2(x+3) + 4(x-1)$. Expand both brackets. Then simplify. How many terms are in your final answer?
0/5QUESTS
Think First
warm-up

Expand and simplify $2(x+3) + 3(x+2)$. Show every step.

Record in workbook.
1
The Big Idea
+5 XP to read

Expand each bracket separately, then collect like terms. Two skills, one problem. Expand first, simplify second.

$2(x+3) + 4(x-1)$: expand to $2x+6+4x-4$, then collect: $6x+2$. Expand every bracket before combining.

$2(x+3)$ + $4(x-1)$ STEP 1: EXPAND $2x + 6 + 4x - 4$ STEP 2: SIMPLIFY $6x + 2$
$2(x+3) + 4(x-1) = 6x + 2$
Expand ALL first
Never collect terms before expanding. Complete expansion first.
Then collect like terms
After expanding, group and combine matching terms.
Track signs
$+4(x-1) = +4x-4$. The sign in front belongs to the bracket.
2
What You'll Master
objectives

Know

  • How to expand multiple brackets
  • That expansion comes before simplifying
  • How signs affect each bracket

Understand

  • Why we expand before collecting
  • How subtraction changes bracket signs
  • That the final answer should be fully simplified

Can Do

  • Expand and simplify expressions with 2+ brackets
  • Handle subtracted brackets
  • Check answers by substitution
3
Words You Need
vocabulary
ExpandRemove brackets using the distributive law.
SimplifyCollect like terms after expanding. No brackets left.
Multiple BracketsTwo or more bracket groups. Expand each separately.
Subtracted BracketA bracket with a minus sign before it. Flip all signs inside.
Like TermsTerms with the same variable part. Combine after expanding.
Fully SimplifiedNo brackets, no like terms left to combine.
4
Spot the Trap
heads-up

Wrong: $2(x+3) + 4(x-1) = 2x+3+4x-1 = 6x+2$

Right: $= 2x+6+4x-4 = 6x+2$. The 3 and 1 must ALSO be multiplied!

Wrong: $3(x+2) - (x-1) = 3x+6-x-1$

Right: $= 3x+6-x+1 = 2x+7$. Minus bracket flips ALL signs!

5
The Two-Step Method
+5 XP

Step 1: Expand every bracket. Step 2: Collect like terms.

$3(x+2) + 2(x-1)$ Original expression $= 3x + 6 + 2x - 2$ Step 1: Expand both brackets $= 5x + 4$ Step 2: Collect like terms ($3x+2x=5x$, $6-2=4$)
6
Subtracted Brackets
+5 XP

When a bracket is subtracted, flip every sign inside after expanding.

$3(x+2) - (x-1) = 3x + 6 - x + 1 = 2x + 7$ $-(x-1) = -x + 1$. The $-1$ becomes $+1$! $3x - x = 2x$ and $6 + 1 = 7$
Try It: $2(x+1) - 3(x-2)$.Ans: $2x+2-3x+6 = -x+8$
7
Three or More Brackets
+5 XP

Expand each bracket one at a time, then collect all like terms at the end.

$2(x+1) + 3(x+2) - (x-1) = 2x+2+3x+6-x+1 = 4x+9$ $x$-terms: $2+3-1=4$. Constants: $2+6+1=9$. Expand each bracket, then combine everything at the end.
8
Quick Reference Table
+5 XP
ExpressionExpandedSimplified
$2(x+3)+4(x-1)$$2x+6+4x-4$$6x+2$
$3(x+2)-(x-1)$$3x+6-x+1$$2x+7$
$2(x+1)+3(x+2)-(x-1)$$2x+2+3x+6-x+1$$4x+9$
Watch Me Solve It · Full expansion
+15 XP per step
Q
PROBLEM
Expand and simplify $2(3x-1) - 3(x+4)$.
  1. 1
    Expand the first bracket
    $2(3x-1) = 6x - 2$
    $2 \times 3x = 6x$ and $2 \times (-1) = -2$.
  2. 2
    Expand the second bracket
    $-3(x+4) = -3x - 12$
    $-3 \times x = -3x$ and $-3 \times 4 = -12$. Note the minus stays.
  3. 3
    Write the full expression
    $6x - 2 - 3x - 12$
    Combine both expansions. No brackets left.
  4. 4
    Collect like terms
    $x$-terms: $6x - 3x = 3x$. Constants: $-2 - 12 = -14$
    $6 - 3 = 3$. $-2 + (-12) = -14$.
  5. 5
    Final answer
    $3x - 14$
    Check: $x=1$. Original: $2(3-1)-3(1+4) = 4-15 = -11$. Answer: $3-14 = -11$ ✓
Answer$3x - 14$
9
Common Pitfalls
heads-up
$2(x+3)+4(x-1) = 2x+3+4x-1$
Didn't multiply the constants! 2 must multiply 3, 4 must multiply -1.
Fix: use arrows. Every term inside gets multiplied by the outside term.
$3(x+2)-(x-1) = 3x+6-x-1$
Forgot to flip signs for subtracted bracket. $-(x-1) = -x+1$ not $-x-1$.
Fix: minus bracket = flip ALL signs. Write it out: $-(x-1) = -x+1$.
Collecting before expanding
$2(x+3)+4(x-1) \\\ 6(x+3-1) = 6(x+2)$
Fix: expand first, collect second. Never collect across brackets!

How are you completing this lesson?

D
Brain Trainer · Mixed
4 problems
  1. 1 Expand and simplify $2(x+3) + 3(x+1)$.

    $2x+6+3x+3 =$ $5x+9$$5x+9$
  2. 2 Expand and simplify $4(2x-1) - 2(x+3)$.

    $8x-4-2x-6 =$ $6x-10$$6x-10$
  3. 3 Expand and simplify $3(x+2) - (x-1)$.

    $3x+6-x+1 =$ $2x+7$$2x+7$
  4. 4 Expand and simplify $2(x+1) + 3(x-2) - (x+4)$.

    $2x+2+3x-6-x-4 =$ $4x-8$$4x-8$
Complete in workbook.
1
Multiple Choice
+10 XP
$2(x+3) + 3(x+1) = $
2
Multiple Choice
+10 XP
$3(2x+1) - (x-2) = $
3
Multiple Choice
+10 XP
$2(x-1) + 3(x+2) - (x-3) = $
4
Multiple Choice
+10 XP
$4(2x-3) - 2(3x-1) = $
5
Multiple Choice
+10 XP
A student writes $2(x+3)+4(x-1) = 2x+3+4x-1$. What is the error?
Show Your Working
9 marks total
Apply Medium 2 MARKS

Q6. Expand and simplify $3(x+2) + 2(x+1)$.

Answer in your workbook.
Apply Medium 3 MARKS

Q7. Expand and simplify $2(3x-1) - 3(x+4)$.

Answer in your workbook.
Apply Medium 4 MARKS

Q8. The perimeter of a triangle is $2(x+3) + 3(x+1) + (x-2)$. Simplify and find the perimeter when $x=2$.

Answer in your workbook.
Apply Hard 3 MARKS

Stretch. If $2(x+3) + k(x-1) = 7x+5$, find the value of $k$.

Answer in your workbook.
Stretch Challenge · +25 XP, +10 coins

Extension Problems

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