Question

Evsluate the following products without multiplying directly (85×86)​

Answer 1

Answer:

(85×86).

(80+5)×(80+6).

using identity, (x+a)((x+b)=x^2+(a+b)x+ab.

x=80, a=5, b=6.

(80+5)(80+6)=(80)^2+(5+6)(80)+(5)(6).

=(6400)+(11)(80)+(30).

=(6400)+(880)+(30).

=7310.

Answer:- (85×86)=(80+5)×(80+6)=7310.