Answer:
[tex]y^2-10xy-9x^2[/tex]
Step-by-step explanation:
We want to subtract [tex]7x^2 -5xy+8y^2[/tex] from [tex]-2x^2-15xy+9y^2[/tex].
We set up the subtraction problem as follows:
[tex](-2x^2-15xy+9y^2)-(7x^2-5xy+8y^2)[/tex].
We expand the brackets to obtain;
[tex]=-2x^2-15xy+9y^2-7x^2+5xy-8y^2[/tex].
We regroup the terms to obtain;
[tex]=9y^2-8y^2-15xy+5xy-2x^2-7x^2[/tex].
We now simplify to obtain;
[tex]=y^2-10xy-9x^2[/tex].
