Question

Subtract the sum of x2−3xy−y2 and 2x2+5xy−4y2 from 6x2−7xy+8y2

Answer 1

Answer in image

Explanation:

Answer in image

Answer 2

`3x^2-9xy+13y^2`

Explanation:

We begin with :
`6x^2-7xy+8y^2-[(x^2-3xy-y^2)+(2x^2+5xy-4y^2)]`

First, let us add the two portions within the brackets. To do this, we need to just combine the like terms

`6x^2-7xy+8y^2-[(x^2-3xy-y^2)+(2x^2+5xy-4y^2)]\\\\6x^2-7xy+8y^2-[3x^2+2xy-5y^2]`

Next, we need to distribute the negative to all the terms within the brackets

`6x^2-7xy+8y^2-[3x^2+2xy-5y^2]\\\\6x^2-7xy+8y^2-3x^2-2xy+5y^2`

Now we can combine the like terms again

`6x^2-7xy+8y^2-3x^2-2xy+5y^2\\\\3x^2-9xy+13y^2`