Question

Use (a-b)²=a²-2ab+b²,find;99²

Answer 1

Answer:

(99)² = (100-1)²

so, (a-b)² = a²-2ab+b²

(100-1)² = (100)² -2×100×1 + (1)²

= 10000 - 200 + 1

= 9801

hope this helps you

Answer 2

(99)^2=(100-1)^2
It implies using the given identity,
(100-1)^2=(100)^2+(1)^2-2(100)(1)
=10000+1-200
=10001-200=801