if 2x+y=-5,prove that 8x^3+y^3-30xy+125=0 i need solution plz anyone provude me the solution
jashangunpreet:
ppz anyine solve this
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Given Equation is : 2x + y = -5.
On cubing both sides, we get
= > (2x + y)^3 = (-5)^3
We know that (a + b)^3 = (a)^3 + (b)^3 + 3ab(a + b)
= > (2x)^3 + (y)^3 + 3(2x)(y)(2x + y) = -125
= > 8x^3 + y^3 + 6xy(2x + y) = -125
= > 8x^3 + y^3 + 6xy(-5) = -125
= > 8x^3 + y^3 -30xy = -125
= > 8x^3 + y^3 - 30xy + 125 = 0.
Hope this helps!
On cubing both sides, we get
= > (2x + y)^3 = (-5)^3
We know that (a + b)^3 = (a)^3 + (b)^3 + 3ab(a + b)
= > (2x)^3 + (y)^3 + 3(2x)(y)(2x + y) = -125
= > 8x^3 + y^3 + 6xy(2x + y) = -125
= > 8x^3 + y^3 + 6xy(-5) = -125
= > 8x^3 + y^3 -30xy = -125
= > 8x^3 + y^3 - 30xy + 125 = 0.
Hope this helps!
:-)
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