28r^2-16r+21r-12=

Solution for 28r^2-16r+21r-12= equation:

Simplifying
28r2 + -16r + 21r + -12 = 0

Reorder the terms:
-12 + -16r + 21r + 28r2 = 0

Combine like terms: -16r + 21r = 5r
-12 + 5r + 28r2 = 0

Solving
-12 + 5r + 28r2 = 0

Solving for variable 'r'.

Factor a trinomial.
(-3 + -4r)(4 + -7r) = 0

Subproblem 1
Set the factor '(-3 + -4r)' equal to zero and attempt to solve:

Simplifying
-3 + -4r = 0

Solving
-3 + -4r = 0

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

Add '3' to each side of the equation.
-3 + 3 + -4r = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -4r = 0 + 3
-4r = 0 + 3

Combine like terms: 0 + 3 = 3
-4r = 3

Divide each side by '-4'.
r = -0.75

Simplifying
r = -0.75
Subproblem 2
Set the factor '(4 + -7r)' equal to zero and attempt to solve:

Simplifying
4 + -7r = 0

Solving
4 + -7r = 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 + -7r = 0 + -4

Combine like terms: 4 + -4 = 0
0 + -7r = 0 + -4
-7r = 0 + -4

Combine like terms: 0 + -4 = -4
-7r = -4

Divide each side by '-7'.
r = 0.5714285714

Simplifying
r = 0.5714285714
Solution
r = {-0.75, 0.5714285714}