Question

Factorise by using formula:

$(4.5{)}^2-(1.5{)}^2$

Answer 1

Formula $a^2-b^2=(a+b)(a-b)$
Hence, ${\left(4.5\right)}^2-(1.5{)}^2=(4.5+1.5\left)\right(4.5-1.5)=6\times 3=18$