Math help...Algebra 2?

(x + 5y)^3
= (x + 5y)(x + 5y)(x + 5y)
= (x*x + 5y*x + x*5y + 5y*5y)(x + 5y)
= (x^2 + 5xy + 5xy + 25y^2)(x + 5y)
= (x^2 + 10xy + 25y^2)(x + 5y)
= x^2*x + 10xy*x + 25y^2*x + x^2*5y + 10xy*5y + 25y^2*5y
= x^3 + 10x^2y + 25xy^2 + 5x^2y + 50xy^2 + 125y^3
= x^3 + 10x^2y + 5x^2y + 25xy^2 + 50xy^2 + 125y^3
= x^3 + 15x^2y + 75xy^2 + 125y^3

Expand it, (x+5y)(x+5y)(x+5y).

x^3 + 125y^3

(x + 5y) (x² + 10xy + 25y²)

x³ + 10 x²y + 25 xy²
____ 5 x²y + 50 xy² + 125 y³

x³ + 15 x²y + 75 xy² + 125 y³

(x+5y)(x+5y)(x+5y)
x^3+125y^3
i think

x^3 + 3(x)(5y)^2 + 3(5y)(x)^2 + (5y)^3
x^3 + 75y^2x + 15yx^2 + 125y^3

From (a + b)³ = a² + 3a²b + 3ab² + b²
(x + 5y)³ = (x)² + 3(x)²(5b) + 3(x)(5b)² + (5b)²
(x + 5y)³ = x² + 15x²b + 75xb² + 125b²

Try writing it out

(x+5y)(x+5y)(x+5y)

i think its

x^3 +25xy^2 + 5x^2y+125y


just times everything by everything in opposing brackets

(x+5y)^3 use FOIL
= (x+5y)(x^2 +10xy + 25y^2)
= (x)(x^2 +10xy + 25y^2) + (5y)(x^2 +10xy + 25y^2)
= (x^3 +10yx^2 + 25xy^2) + (5yx^2 + 50xy^2 + 125y^3)
= x^3 + 15yx^2 + 75xy^2 + 125y^3

or use pascals triangle to get:
x^3 + 3(x^2)(5y) + 3(x)((5y)^2) + (5y)^3
= x^3 +15yx^2 + 3x(25y^2) + 125y^3
= x^3 + 15yx^2 + 75 xy^2 + 125y^3

x^3 + 15x^(2)y + 75xy^(2) + 125y^3