Question

Using (x+a)(x+b)=x sq+(a+b)x+ab,find 5.1×5.2

Answer 1

(x+a)(x+b) = x²+(a+b)x+ab
5.1×5.2
= (5+0.1)(5+0.2)
=(5)²+5×0.2+0.1×5+(0.1×0.2)
=25+(0.1+0.2)5+0.02
=25.02+0.3
=25.05