Answer:
1) [tex]49 {a}^{2} - 16 {b}^{2} [/tex]
2) [tex]251502[/tex]
Step-by-step explanation:
a) Question :-[tex](7a - 4b)(7a + 4b)[/tex]
Identity used here :-[tex](a + b)(a - b) = {a}^{2} - {b}^{2} [/tex]
So,
[tex](7a + 4b)(7a - 4b)[/tex]
[tex]=> {(7a)}^{2} - {(4b)}^{2} [/tex]
[tex]=> 49 {a}^{2} - 16 {b}^{2} [/tex]
b) Question :- [tex]501 \times 502[/tex]
Identity used here :-[tex](x + a)(x + b) = {x}^{2} + (a + b)x + ab[/tex]
So,
[tex]501 \times 502 = (500 + 1)(500 + 2)[/tex]
[tex] = > {(500)}^{2} + (1 + 2)500 + 1 \times 2[/tex]
[tex] = > 250000 + 1500 + 2[/tex]
[tex] = > 251502[/tex]
