Question

4. Kameron solved the problem (3 x² + 2 x+1)-(x2-3x+4) using the following

work.
(3x2+2x+1)-(x²-3x+4)
3x²+2x+1-x²-3x+4
3x²-x²+2x-3x+1+4
2x²-x+5
Review Kameron's work and determine if his answer is correct, or if incorrect,
the reason why.

Answer 1

His answer is incorrect; his second step should read '3x²+2x+1-x²+3x-4', not '3x²+2x+1-x²-3x+4'.

Explanation:

(3x² + 2x + 1) - (x² - 3x + 4)

First, multiply the second brackets by the minus:

3x² + 2x + 1 - x² + 3x - 4

We notice that Kameron didn't multiply everything in the second brackets by the minus, only the first term. So his answer will be incorrect. The rest of the method to solve the problem is below.

Next step is to group similar terms together:

3x² - x² + 2x + 3x + 1 - 4

Then evaluate!

2x² + 5x -3