Question

Q8. If a = 3 and b = 5, find the value of: (a) a2 - b2 (b) a3 + b3 + 2ab (c) 7a²b - 3ab (d) a² + b2 - ab -​

Answer 1

solution

3²-5² = 9 -25 = 8 = 2³

3³+2³=+ 2×3×5 = 27 + 8 + 30 = 653

Hello the answer is 653

Pls mark me brainlist pls

Answer 2

EXPLANATION.

If a = 3 and b = 5.

(1) : a² - b².

As we know that,

We can write equation as,

⇒ (a² - b²) = (a - b)(a + b).

Put the values in the equation, we get.

⇒ (a² - b²) = (3 - 5)(3 + 5).

⇒ (a² - b²) = (-2)(8).

⇒ (a² - b²) = - 16.

(2) : a³ + b³.

As we know that,

We can write equation as,

⇒ (a³ + b³) = (a + b)(a² - ab + b²).

⇒ (a³ + b³) = (3 + 5)[(3)² - (3)(5) + (5)²].

⇒ (a³ + b³) = (8)[9 - 15 + 25].

⇒ (a³ + b³) = (8)[34 - 15].

⇒ (a³ + b³) = (8)[19].

⇒ (a³ + b³) = 152.

(3) : 7a²b - 3ab.

As we know that,

We can write equation as,

⇒ (7a²b - 3ab) = [7(3)²(5) - 3(3)(5)].

⇒ (7a²b - 3ab) = [(7)(9)(5) - 3(3)(5)].

⇒ (7a²b - 3ab) = [315 - 45].

⇒ (7a²b - 3ab) = 270.

(4) : a² + b² - ab.

As we know that,

We can write equation as,

⇒ a² + b² - ab = (3)² + (5)² - (3)(5).

⇒ a² + b² - ab = 9 + 25 - 15.

⇒ a² + b² - ab = 34 - 15.

⇒ a² + b² - ab = 19.

$\huge\red{➳Ṧřîⅉꫝᾇñ ࿐}$