Question

please Legends answer this​

Answer 1

Step-by-step explanation:

(1)

Given Equation is a - b = 3 and ab = 4

a³ - b³ = (a - b)³ + 3ab(a - b)

          = 3³ + 3(4)(3)

          = 27 + 36

        = 63

(2)

Given: 2a - 3b = 3

On cubing both sides, we get

⇒ (2a - 3b)³ = 3³

⇒ 8a³ - 27b³ - 3(2a)(3b)(2a - 3b) = 27

⇒ 8a³ - 27b³ - 18(ab)(2a - 3b) = 27

⇒ 8a³ - 27b³ - 108 = 27

⇒ 8a³ - 27b³ = 135

Answer 2

1) $\sf{a-b=3}$

$\sf{ab=4}$

a³ - b³ = (a - b)³ + 3ab (a - b)

$\sf{ {a}^{3} - {b}^{3} = {3}^{3} + 3(4)(3)}$

$\sf{ {a}^{3} - {b}^{3} =27 + 36}$

$\fbox{ \sf{a}^{3} - {b}^{3} =63}$

2)2a - 3b = 3

ab = 2

cubing,

$\sf{ {(2a-3b)}^{3} = {3}^{3} }$

$\sf{ {(2a)}^{3} - {(3b)}^{3} - 3(2a)(3b)(2a - 3b)} = 27$

$\sf{ {8a}^{3} - {27b}^{3} - 18(2)(3) = 27}$

8a³ - 27b³ = 27 + 108

8a³ - 27b³ = 135