Question

2a+3b=4 then 8a³+27b³+72ab=?

Answer 1

Answer:

the right answer is 4 answer

Answer 2

The correct answer is 64.

Given: The equation = 2a+3b=4.

To Find: The value of 8a³+27b³+72ab.

Solution:

The equation = 2a+3b=4

Cube both the sides of equation.

$(2a+3b)^{3}=64$

$8a^{3}+27b^{3}+3(2a)(3b)(2a+3b)=64$

$8a^{3}+27b^{3}+18ab(2a+3b)=64$

Now as 2a+3b=4,put the value of 2a+3b in the equation.

$8a^{3}+27b^{3}+18ab(4)=64$

$8a^{3}+27b^{3}+72ab=64$

Hence, the value of  $8a^{3}+27b^{3}+72ab$ is 64.

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