Question

Using identities evaluate 99²​

Answer 1

Answer:

$\rm 9801$

Step-by-step explanation:

By using identity,

$\boxed{\rm (a-b)^2 = a^2+b^2-2ab}$

$\rm 99^2 = (100-1)^2$

$\rm (100-1)^2= 100^2+1^2-2(100)(1)$

$\rm = 10000+1-200$

$\rm = 9800+1$

$\rm = 9801$

Answer 2

$\blue{\large\bf\underline{Answer \: and \: Explaination}}$

$\sf{{99}^{2}}$

$\sf = {{(100 - 1)}^{2}}$

⬇️

$\sf{It \: is \: in \: the \: form \: {(a - b)}^{2} \: and \: {(a - b)}^{2} = {a}^{2} - 2ab + {b}^{2}}$

$\sf{a = 100}$

$\sf{b = 1}$

$\sf{{(100 - 1)}^{2} = {100}^{2} - 2(100)(1) + {1}^{2}}$

$\sf{ = 10000 - 200 + 1}$

$\sf{ = 10000 - 199}$

$\sf{ = 9801}$

$\blue{\sf\boxed{\sf{\therefore{Answer = 9801}}}}$

$\bf\pink{\underline{✌Be \: happy✌}}$