Question

36.Find the following using suitable identities.

a) (7a – 4b) (7a + 4b)
b) 501 x 502
Would appreciate if you send a pic of the solutions<3

Answer 1

1)
`49 {a}^(2) - 16 {b}^(2)`

2)
`251502`

Explanation:

a) Question :-
`(7a - 4b)(7a + 4b)`

Identity used here :-
`(a + b)(a - b) = {a}^(2) - {b}^(2)`

So,

`(7a + 4b)(7a - 4b)`

`=> {(7a)}^(2) - {(4b)}^(2)`

`=> 49 {a}^(2) - 16 {b}^(2)`

b) Question :-
`501 * 502`

Identity used here :-
`(x + a)(x + b) = {x}^(2) + (a + b)x + ab`

So,

`501 * 502 = (500 + 1)(500 + 2)`

`= > {(500)}^(2) + (1 + 2)500 + 1 * 2`

`= > 250000 + 1500 + 2`

`= > 251502`