Question

How to find difference of
${21}^{2} - {20}^{2}$
without actually subtracting it?

Answer 1

Heya ✋

Let see your answer !!!!

$(21) ^{2} - (20) ^{2} \\ we \: apply \: this \: formula \\ a ^{2} -b ^{2} = (a + b)(a - b) \\ = (21 + 20)(21 - 20) \\ = 41 \times 1 \\ = 41$




Thanks :)))))

Answer 2

Hi ,

Here is your answer !
__________________________

Using the identity

[ a² - b² = (a + b) (a - b) ]

We have ,

21² - 20² = (21 + 20) (21 - 20)

= 41 × 1 = 41

=> 21² - 20² = 41