4r(5r-4)=0

Solution for 4r(5r-4)=0 equation:

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

Reorder the terms:
4r(-4 + 5r) = 0
(-4 * 4r + 5r * 4r) = 0
(-16r + 20r2) = 0

Solving
-16r + 20r2 = 0

Solving for variable 'r'.

Factor out the Greatest Common Factor (GCF), '4r'.
4r(-4 + 5r) = 0

Ignore the factor 4.
Subproblem 1
Set the factor 'r' equal to zero and attempt to solve:

Simplifying
r = 0

Solving
r = 0

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

Simplifying
r = 0
Subproblem 2
Set the factor '(-4 + 5r)' equal to zero and attempt to solve:

Simplifying
-4 + 5r = 0

Solving
-4 + 5r = 0

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

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

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

Combine like terms: 0 + 4 = 4
5r = 4

Divide each side by '5'.
r = 0.8

Simplifying
r = 0.8
Solution
r = {0, 0.8}