Question

A^3=4a^2+21a
need help please

Answer 1

Hello!

`\large\boxed{a = 0, -3, 7}`

a³ = 4a² + 21a

Move all "a" to one side:

0 = -a³ + 4a² + 21a

Factor out "-a" from the equation:

0 = -a(a² - 4a - 21)

Solve for a by factoring:

0 = -a(a - 7)(a + 3)

Solve for the roots by setting each factor equal to 0:

-a = 0

a = 0

a - 7 = 0

a = 7

a + 3 = 0

a = -3

Solutions: a = 0, -3, 7