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

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

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

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

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

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

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

Solving
-20 + -9a + 20a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(-4 + -5a)(5 + -4a) = 0

Subproblem 1
Set the factor '(-4 + -5a)' equal to zero and attempt to solve:

Simplifying
-4 + -5a = 0

Solving
-4 + -5a = 0

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

Add '4' to each side of the equation.
-4 + 4 + -5a = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -5a = 0 + 4
-5a = 0 + 4

Combine like terms: 0 + 4 = 4
-5a = 4

Divide each side by '-5'.
a = -0.8

Simplifying
a = -0.8
Subproblem 2
Set the factor '(5 + -4a)' equal to zero and attempt to solve:

Simplifying
5 + -4a = 0

Solving
5 + -4a = 0

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

Add '-5' to each side of the equation.
5 + -5 + -4a = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -4a = 0 + -5
-4a = 0 + -5

Combine like terms: 0 + -5 = -5
-4a = -5

Divide each side by '-4'.
a = 1.25

Simplifying
a = 1.25
Solution
a = {-0.8, 1.25}