Question

From the sum of polynomials 3a2−ab−2b2 and 2a2+5ab−3b2 subtract polynomial a2−3ab−4b2.

Answer 1

`4a^2+7ab-b^2`

Explanation:

First, we will sum

`3a^2-ab-2b^2`

and

`2a^2+5ab-3b^2`

Then, from that sum, we will SUBTRACT
`a^2-3ab-4b^2`

First, lets take the sum by combining like terms:

`(3a^2-ab-2b^2)+(2a^2+5ab-3b^2)=5a^2+4ab-5b^2`

Now, lets do the subtraction:

`(5a^2+4ab-5b^2)-(a^2-3ab-4b^2)\\=5a^2+4ab-5b^2-a^2+3ab+4b^2\\=4a^2+7ab-b^2`

This is the answer.