Unit 4, Lesson 4 Cool-down 4.4 Mis-Steps Lin solved the equation 8( x - 3 ) + 7 = 2x( 4 - 17 ) incorrectly.
Find the errors in her solution. What should her answer have been?

Lin's solution:

8( x - 3 ) + 7 = 2x( 4 - 17 )

8( x - 3 ) + 7 = 2x(13 )

8x - 24 + 7 = 26x

8x - 17 = 26x

-17 = 34x

-½ = x

Let’s do the equation ourselves

8( x - 3 ) + 7 = 2x( 4 - 17 )

Let’s condense as she did

8( x - 3 ) + 7 = 2x ( -13 )

Distribute

8x - 24 + 7 = -26x

Combine like terms

8x - 17 = -26x

Move x to one side

-17 = -34x

Divide by -34

1/2 = x

Lin had subtracted 4 - 17 incorrectly, having the number 13 as a positive instead of a negative number. Her answer should have been 1/2 instead of -1/2.