Question

factorise (2x+5y)²-1

Answer 1

(2x+5y)^2-1
It is the form of (a+b)^2 -1
(a+b)^2=a^2+2ab+b^2 -1
(2x)^2+2×2x×5y+(5y)^2-1
4x^2+20xy+25y^2-1

Answer 2

(2x+5y)^2-1

It is the form of (a+b)^2 -1

(a+b)^2=a^2+2ab+b^2 -1

(2x)^2+2×2x×5y+(5y)^2-1

4x^2+20xy+25y^2-1