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Algebra 1 Honors · Lesson 2.1

Multi-Step Equations

How it works

An equation asserts equal values. Applying the same reversible operation to both sides preserves its solution set. Distribute and combine like terms before isolating the variable. After solving, substitute into the original equation, particularly when negative signs appear.

a=b ⟹ a+c=b+ca=b\ \Longrightarrow\ a+c=b+c

Worked examples

Example 1

Solve 3(x−2)+4=16\displaystyle 3(x-2)+4=16.

Distribute: 3x−6+4=16\displaystyle 3x-6+4=16. Thus 3x=18\displaystyle 3x=18 and x=6\displaystyle x=6. Check: 3(6−2)+4=16\displaystyle 3(6-2)+4=16.

Example 2

Solve 5x+2=2x+14\displaystyle 5x+2=2x+14.

Subtract 2x\displaystyle 2x and 2\displaystyle 2: 3x=12\displaystyle 3x=12. Therefore x=4\displaystyle x=4.

Problems

Problem 2.1.1

Solve 4(x+1)−3=13\displaystyle 4(x+1)-3=13.

Show worked solution

4x+1=13\displaystyle 4x+1=13, so 4x=12\displaystyle 4x=12 and x=3\displaystyle x=3.

Problem 2.1.2

Solve 7−2x=19\displaystyle 7-2x=19.

Show worked solution

−2x=12\displaystyle -2x=12, so x=−6\displaystyle x=-6. Check: 7−2(−6)=19\displaystyle 7-2(-6)=19.

Problem 2.1.3

Solve 2(x+3)=2x+6\displaystyle 2(x+3)=2x+6.

Show worked solution

Both sides simplify to 2x+6\displaystyle 2x+6, so every real number is a solution.

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