Question

9) Andrew scored a 95 on his last test and the only question he answered incorrectly is listed below.

Answer the following questions 9(a) and 9(b) as they relate to Andrew's work.
(a) Read through the question and Andrew's work. (b) Explain what he did wrong and what he should
Find and circle his mistake.
have done.
Evaluate: 3(r + 2) (4-r) when r = 1.
Andrew's work:
= 3(r + 2)(4-r)
= 3(1+2)(4-1)
= 3(3)(3)
= 9

Answer 1

His mistake is 3(3)(3) = 9

He should have wrote 27.

Explanation:

Lets review his work:

3(r+2)(4-r)

Substitute 1 for r

3(1+2)(4-1)

Simplify

3(3)(3)

3*3*3 is 27, not 9 so that is his mistake.

He should have multiplied 3*3*3 =27.

Hope this helps!