Question

36.Find the following using suitable identities.

Answer 1

Answer:

1) $49 {a}^{2} - 16 {b}^{2}$

2) $251502$

Step-by-step 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 :- $501 \times 502$

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

So,

$501 \times 502 = (500 + 1)(500 + 2)$

$= > {(500)}^{2} + (1 + 2)500 + 1 \times 2$

$= > 250000 + 1500 + 2$

$= > 251502$