Question

find the value of 125x^3-8y^3 if 5x-2y=7 and xy=12​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Given,

$5x-2y=7$ and $xy=12$

We can find the value of $125x^{3}-8y^{3}$

We can use the $(a-b)^{3}=a^{3}-b^{3}-3ab(a-b)$ formula to prove the given expression,

Here, $a=5x, b=2y$

Substitute the above values in the formula,

$(5x-2y)^{3} =(5x)^{3}-(2y)^{2}-3\times5x\times2y(5x-2y)$

We have, $5x-2y=7$ and $xy=12$

$(7)^{3}=125x^{3}-8y^{3}-360\times7\\125x^{3}-8y^{3}=343+2520\\125 x^{3}-8y^{3}=2863$

Therefore, the value of $125x^{3}-8y^{3}$ is $2863$.