=-9(4a-5)(4a+5)

Solution for =-9(4a-5)(4a+5) equation:

Simplifying
0 = -9(4a + -5)(4a + 5)

Reorder the terms:
0 = -9(-5 + 4a)(4a + 5)

Reorder the terms:
0 = -9(-5 + 4a)(5 + 4a)

Multiply (-5 + 4a) * (5 + 4a)
0 = -9(-5(5 + 4a) + 4a * (5 + 4a))
0 = -9((5 * -5 + 4a * -5) + 4a * (5 + 4a))
0 = -9((-25 + -20a) + 4a * (5 + 4a))
0 = -9(-25 + -20a + (5 * 4a + 4a * 4a))
0 = -9(-25 + -20a + (20a + 16a2))

Combine like terms: -20a + 20a = 0
0 = -9(-25 + 0 + 16a2)
0 = -9(-25 + 16a2)
0 = (-25 * -9 + 16a2 * -9)
0 = (225 + -144a2)

Solving
0 = 225 + -144a2

Solving for variable 'a'.

Move all terms containing a to the left, all other terms to the right.

Add '144a2' to each side of the equation.
0 + 144a2 = 225 + -144a2 + 144a2
Remove the zero:
144a2 = 225 + -144a2 + 144a2

Combine like terms: -144a2 + 144a2 = 0
144a2 = 225 + 0
144a2 = 225

Divide each side by '144'.
a2 = 1.5625

Simplifying
a2 = 1.5625

Take the square root of each side:
a = {-1.25, 1.25}