Question

if 2a-3b =3 and ab=2,find the value of 8a3-27b3

Answer 1

Answer:

Step-by-step explanation:

This the ans

Answer 2

Answer:

8a³ - 27b³ = 135

Step-by-step explanation:

Given,

2a - 3b = 3 and ab = 2

To find,

$8a^3-27b^3$

Recall the formula

$(x - y)^3 = x^3 - y^3 - 3xy (x-y)$

Solution

We have

$(x - y)^3 = x^3 - y^3 - 3xy (x-y)$

Substituting the value of x = 2a and  y = 3b we get

$(2a - 3b)^3 = (2a)^3 - (3b)^3 - 3(2a)(3b) (2a-3b)$

$(2a - 3b)^3 = 8a^3 - 27b^3 - 18ab (2a-3b)$

Substitute the values of 2a - 3b and ab in the above equation we get

3³ = 8a³ - 27b³ - 18  ×2×3

27 =  8a³ - 27b³ - 108

8a³ - 27b³ = 27+108

=135

∴ 8a³ - 27b³ = 135

#SPJ3