Answer/Step-by-step explanation:
Let's work out the subtraction of the polynomial to find out where the error is and the correct result we should have.
6x² - 4x - 5
- 3x² - 7x + 2
= [6x² - 3x²] [-4x -(-7x)] [-5 -(+2)]
= 3x² + 3x - 7
The error that was made in the subtraction given in the question was that the negative signs before the terms, 7x and 5 were ignored while subtracting.
The sign is very important, it defines the value of the term.
We can choose to solve the problem in another way shown below:
(6x² - 4x - 5) - (3x² - 7x + 2)
Distributive the negative sign in the second polynomial
6x² - 4x - 5 - 3x² + 7x - 2
Combine like terms
6x² - 3x² - 4x + 7x - 5 - 2
3x² + 3x - 7