(7r-5)(8r+1)=

Solution for (7r-5)(8r+1)= equation:

Simplifying
(7r + -5)(8r + 1) = 0

Reorder the terms:
(-5 + 7r)(8r + 1) = 0

Reorder the terms:
(-5 + 7r)(1 + 8r) = 0

Multiply (-5 + 7r) * (1 + 8r)
(-5(1 + 8r) + 7r * (1 + 8r)) = 0
((1 * -5 + 8r * -5) + 7r * (1 + 8r)) = 0
((-5 + -40r) + 7r * (1 + 8r)) = 0
(-5 + -40r + (1 * 7r + 8r * 7r)) = 0
(-5 + -40r + (7r + 56r2)) = 0

Combine like terms: -40r + 7r = -33r
(-5 + -33r + 56r2) = 0

Solving
-5 + -33r + 56r2 = 0

Solving for variable 'r'.

Factor a trinomial.
(-1 + -8r)(5 + -7r) = 0

Subproblem 1
Set the factor '(-1 + -8r)' equal to zero and attempt to solve:

Simplifying
-1 + -8r = 0

Solving
-1 + -8r = 0

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

Add '1' to each side of the equation.
-1 + 1 + -8r = 0 + 1

Combine like terms: -1 + 1 = 0
0 + -8r = 0 + 1
-8r = 0 + 1

Combine like terms: 0 + 1 = 1
-8r = 1

Divide each side by '-8'.
r = -0.125

Simplifying
r = -0.125
Subproblem 2
Set the factor '(5 + -7r)' equal to zero and attempt to solve:

Simplifying
5 + -7r = 0

Solving
5 + -7r = 0

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

Add '-5' to each side of the equation.
5 + -5 + -7r = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -7r = 0 + -5
-7r = 0 + -5

Combine like terms: 0 + -5 = -5
-7r = -5

Divide each side by '-7'.
r = 0.7142857143

Simplifying
r = 0.7142857143
Solution
r = {-0.125, 0.7142857143}