Question

Factorise completely 225-a^2-b^2-2ab

Answer 1

225-a^2-b^2-2ab=0
a^2+b^2+2ab-225=0
(a+b)^2=225
a+b=root225
a+b=15 or-15

Answer 2

225 - a² - b² - 2ab
= 225 - (a² + b² + 2ab)
= (15)² - (a+b)²
= [(15) + (a+b)] [(15) - (a+b)]
= (15+a+b)(15-a-b)