21r^2+r=10

Solution for 21r^2+r=10 equation:

Simplifying
21r2 + r = 10

Reorder the terms:
r + 21r2 = 10

Solving
r + 21r2 = 10

Solving for variable 'r'.

Reorder the terms:
-10 + r + 21r2 = 10 + -10

Combine like terms: 10 + -10 = 0
-10 + r + 21r2 = 0

Factor a trinomial.
(-5 + -7r)(2 + -3r) = 0

Subproblem 1
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
Subproblem 2
Set the factor '(2 + -3r)' equal to zero and attempt to solve:

Simplifying
2 + -3r = 0

Solving
2 + -3r = 0

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

Add '-2' to each side of the equation.
2 + -2 + -3r = 0 + -2

Combine like terms: 2 + -2 = 0
0 + -3r = 0 + -2
-3r = 0 + -2

Combine like terms: 0 + -2 = -2
-3r = -2

Divide each side by '-3'.
r = 0.6666666667

Simplifying
r = 0.6666666667
Solution
r = {-0.7142857143, 0.6666666667}