Question

please somebody answer​

Answer 1

Answer:

HOPE IT HELPS YOU !!!

Step-by-step explanation:

TO FIND :

value of 8x^3 + y^3 - 30xy + 125

if 2x+y=-5

SOLUTION :

8x^3 + y^3 - 30xy + 125 can be rewritten as

(2x)^3 + (y)^3 + (5)^3 - 3*(2x)*(y)*(5)

Using the identity : A^3+B^3+C^3-3ABC = (A+B+C)(A^2+B^2+C^2-AB-BC-CA) we get,

(2x+y+5)[(2x)^2+y^2+5^2-(2x)(y)-(y)(5)-(5)(2x) --------------(1)

In the question it was given that 2x+y=-5

=> 2x+y+5=0

Putting 2x+y+5 in equation(1) we get,

(0) * [(2x)^2+y^2+5^2-(2x)(y)-(y)(5)-(5)(2x)

Therefore 8x^3 + y^3 - 30xy + 125 = 0

Hence the value is zero.