Exercises: Explain Each Step in Solving an Equation

Work through each section in order. Show your work and justify your reasoning where indicated.

Grade 9·21 problems·~35 min·Common Core Math - HS Algebra·standard·hsa-rei-a-1

Work through problems with immediate feedback

Recall / Warm-Up

A student solves $x + 5 = 12$ and gets $x = 7$ . Which step correctly checks this answer?

Subtract 5 from both sides again: $7 - 5 = 2$ . Since $2 \neq 12$ , check again.

Substitute $x = 7$ into the original equation: $7 + 5 = 12$ . Since $12 = 12$ , it checks.

Since $7 < 12$ , the answer is confirmed.

Substitute $x = 7$ into the left side only: $7 + 5 = 12$ . Done.