Question

(3x+y)(x+y)-4y(x-y)

(a-5)(a+1)-(a-6)(a-1)

(2x-b)(3x+b)+(3b-x)(b+x)

(2a+c)(a-3c)+a(2c-a)

(y-10)(y-2)+(y+4)(y-5)

Answer 1

3x^2+3xy+xy+y^2-4xy+4y^2
------  ==   ==    ~~  ==  ~~~
3x^2+5y^2=
(3x+5y)^2