Question

Explain and correct the error made by a student who simplified this expression -2+7(x+8)

5(x+8)
5x+40

Answer 1

7x + 54

Explanation:

Given

- 2 + 7(x + 8)

The student made the error of adding before multiplying, that is

- 2 + 7 = 5 , then multiplying (x + 8) by 5

However, multiplication is performed before addition/ subtraction, thus

- 2 + 7(x + 8) ← distribute by 7

= - 2 + 7x + 56 ← collect like terms

= 7x + 54

Answer 2

The error made by the student was that they didn't distribute the 7 first, they just added -2 and 7. The correct way would be to distribute first:

-2+7(x+8)

-2+7x+56

54+7x

*Hey! Hope this helped : )*