Question

find the value of the following using the formula ​

Answer 1

we know, (a^2 )- (b^2) =(a+b) (a-b)

so..

I. (36^2)-(31^2) = (32+31)(36-31)

63*5

315

k. (42^2)-(9^2) = (42+9)(42-9)

51*33

1683

Answer 2

★  Formula : a² - b² = (a + b)(a - b)

i. Given : 36² - 31²

Here : a = 36 and b = 31

$:\implies$  36² - 31² = (36 + 31)(36 - 31)

$:\implies$  36² - 31² = (67)(5)

$:\implies$  36² - 31² = 335

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k. Given : 42² - 9²

Here : a = 42 and b = 9

$:\implies$  42² - 9² = (42 + 9)(42 - 9)

$:\implies$  36² - 31² = (51)(33)

$:\implies$  36² - 31² = 1683