Algebra 1 : How to solve two-step equations

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #801 : Algebra 1

Solve:  \(\displaystyle \frac{3}{4}x +8 = -4\)

Possible Answers:

\(\displaystyle -\frac{13}{4}\)

\(\displaystyle -\frac{1}{3}\)

\(\displaystyle -1\)

\(\displaystyle -16\)

\(\displaystyle -\frac{16}{3}\)

Correct answer:

\(\displaystyle -16\)

Explanation:

Subtract eight on both sides to isolate the term with the x-variable.

\(\displaystyle \frac{3}{4}x +8 -8= -4-8\)

\(\displaystyle \frac{3}{4}x=-12\)

To isolate the x-variable, we will need to multiply both sides by the reciprocal of the coefficient in front of the x.

\(\displaystyle \frac{3}{4}x \cdot \frac{4}{3}=-12 \cdot \frac{4}{3}\)

Simplify both sides.

\(\displaystyle x= \frac{-48}{3}=-16\)

The answer is:  \(\displaystyle -16\)

Example Question #802 : Algebra 1

Solve the following equation:  \(\displaystyle 4x+9 = 41\)

Possible Answers:

\(\displaystyle \frac{25}{2}\)

\(\displaystyle 28\)

\(\displaystyle -\frac{25}{2}\)

\(\displaystyle -8\)

\(\displaystyle 8\)

Correct answer:

\(\displaystyle 8\)

Explanation:

Subtract nine on both sides to separate the term with the x variable.

\(\displaystyle 4x+9 -9= 41-9\)

Simplify both sides.

\(\displaystyle 4x=32\)

Divide by four on both sides.

\(\displaystyle \frac{4x}{4}=\frac{32}{4}\)

Simplify both fractions.

\(\displaystyle x=8\)

The answer is:  \(\displaystyle 8\)

Example Question #802 : Linear Equations

Solve for \(\displaystyle q\):

\(\displaystyle 14q+11=-3\)

Possible Answers:

\(\displaystyle q=-1\)

\(\displaystyle q=0\)

\(\displaystyle q=1\)

\(\displaystyle q=\frac{-9}{14}\)

\(\displaystyle q=\frac{9}{14}\)

Correct answer:

\(\displaystyle q=-1\)

Explanation:

To solve this problem you need to get \(\displaystyle q\) by itself. The first step to do this is to subtract 11 from both sides to get:

\(\displaystyle 14q=-3-11\)

\(\displaystyle 14q=-14\)

From here you need to divide both sides by 14 to get a final answer of

\(\displaystyle q=-1\)

Example Question #803 : Linear Equations

An arrow is shot according to the trajectory \(\displaystyle -x^2=-16\)

Solve for \(\displaystyle x\).

Possible Answers:

No real solution

\(\displaystyle x=16, -16\)

\(\displaystyle x=2,-2\)

\(\displaystyle x=4\)

\(\displaystyle x=4, -4\)

Correct answer:

\(\displaystyle x=4, -4\)

Explanation:

To simplify this problem you must first divide or multiply both sides by negative one to get:

\(\displaystyle x^2=16\)

From here you must square root both sides, but it is important to remember that when you take the square root you get a positive and negative answer.

So:

\(\displaystyle x= \sqrt{16}\)  so \(\displaystyle x=\pm 4\)

Example Question #804 : Linear Equations

Solve the equation:  \(\displaystyle 4x-8 = 32\)

Possible Answers:

\(\displaystyle -10\)

\(\displaystyle 6\)

\(\displaystyle \frac{1}{10}\)

\(\displaystyle 10\)

\(\displaystyle -6\)

Correct answer:

\(\displaystyle 10\)

Explanation:

Isolate the term with the x variable by adding eight on both sides.

\(\displaystyle 4x-8 +8= 32+8\)

Simplify both sides.

\(\displaystyle 4x=40\)

Divide by four on both sides.

\(\displaystyle \frac{4x}{4}=\frac{40}{4}\)

Simplify each fraction on both sides.

The answer is:  \(\displaystyle x=10\)

Example Question #805 : Linear Equations

Solve the equation:  \(\displaystyle 3x+6=-17\)

Possible Answers:

\(\displaystyle \frac{11}{3}\)

\(\displaystyle -\frac{23}{3}\)

\(\displaystyle \frac{23}{3}\)

\(\displaystyle -\frac{16}{3}\)

\(\displaystyle -\frac{11}{3}\)

Correct answer:

\(\displaystyle -\frac{23}{3}\)

Explanation:

Subtract six from both sides of the equation.

\(\displaystyle 3x+6-6=-17-6\)

Simplify both equations.

\(\displaystyle 3x=-23\)

Divide by three on both sides.

\(\displaystyle \frac{3x}{3}=\frac{-23}{3}\)

Simplify both sides.

The answer is:  \(\displaystyle -\frac{23}{3}\)

Example Question #806 : Linear Equations

Solve the following equation: \(\displaystyle -6x+8 =-14\)

Possible Answers:

\(\displaystyle -\frac{11}{3}\)

\(\displaystyle \frac{3}{11}\)

\(\displaystyle -\frac{3}{11}\)

\(\displaystyle -1\)

\(\displaystyle \frac{11}{3}\)

Correct answer:

\(\displaystyle \frac{11}{3}\)

Explanation:

Subtract eight on both sides.

\(\displaystyle -6x+8-8 =-14-8\)

Simplify both sides.

\(\displaystyle -6x=-22\)

Divide by negative six on both sides.

\(\displaystyle \frac{-6x}{-6}=\frac{-22}{-6}\)

The left side will leave \(\displaystyle x\) by itself. Simplify the right side by common factors.

\(\displaystyle x= \frac{-1 \times 2 \times 11}{-1 \times 2 \times 3}\)

Cancel the like terms in the numerator and denominator.

The answer is: \(\displaystyle \frac{11}{3}\)

Example Question #807 : Linear Equations

Solve the following equation:  \(\displaystyle -6x+9 = -15\)

Possible Answers:

\(\displaystyle -4\)

\(\displaystyle -1\)

\(\displaystyle 1\)

\(\displaystyle 0\)

\(\displaystyle 4\)

Correct answer:

\(\displaystyle 4\)

Explanation:

Subtract nine on both sides.

\(\displaystyle -6x+9-9 = -15-9\)

Simplify both sides.

\(\displaystyle -6x=-24\)

Divide by negative six on both sides.

\(\displaystyle \frac{-6x}{-6}=\frac{-24}{-6}\)

Simplify both sides.

\(\displaystyle x=4\)

The answer is:  \(\displaystyle 4\)

Example Question #811 : Algebra 1

Solve the following equation: \(\displaystyle 3x+6 = -50\)

Possible Answers:

\(\displaystyle -\frac{56}{3}\)

\(\displaystyle -\frac{44}{3}\)

\(\displaystyle -12\)

\(\displaystyle \frac{44}{3}\)

\(\displaystyle \frac{56}{3}\)

Correct answer:

\(\displaystyle -\frac{56}{3}\)

Explanation:

To isolate the \(\displaystyle \textup{x-variable}\), first subtract \(\displaystyle 6\) on both sides.

\(\displaystyle 3x+6 -6= -50-6\)

Simplify both sides.

\(\displaystyle 3x=-56\)

Divide by three on both sides.

\(\displaystyle x =-\frac{56}{3}\)

This fraction is irreducible.

The answer is: \(\displaystyle -\frac{56}{3}\)

Example Question #812 : Linear Equations

Solve the following equation:  \(\displaystyle 2-x =-20\)

Possible Answers:

\(\displaystyle -24\)

\(\displaystyle -18\)

\(\displaystyle 22\)

\(\displaystyle 18\)

\(\displaystyle -22\)

Correct answer:

\(\displaystyle 22\)

Explanation:

To isolate the x-variable, add \(\displaystyle x\) on both sides to move it to the right side and turn the sign into positive so that we won't have to divide by a negative one.

\(\displaystyle 2-x+x =-20+x\)

Simplify both sides.

\(\displaystyle 2=-20+x\)

Add twenty on both sides.

\(\displaystyle 2+20=-20+x+20\)

This will eliminate the negative twenty on the right side.

The answer is:  \(\displaystyle 22=x\)

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