Question

using the formula a-b =a square - 2ab+5 square evaluate 891 square

Answer 1

Hola..!!

${891}^{2} = (900 - 9 )^{2} \\ \: \: \: \: \: \: \: \: \: \: = {900}^{2} - 2 \times 900 \times 9 + {9}^{2} \\ \: \: \: \: \: \: \: \: \: \: = 810000 - 16200 + 81 \\ \: \: \: \: \: \: \: \ko: \: \: = 793881$
Hope it helps..!!

Answer 2

(a-b)^2=a^2-2ab+b^2
(891)^2=(900-9)^2=810000-2(900)(9)+81
=810081-16200
=793881
here a=900,b=9 what is confusion in this question