8x^2+21x-5=4

Solution for 8x^2+21x-5=4 equation:

Simplifying
8x2 + 21x + -5 = 4

Reorder the terms:
-5 + 21x + 8x2 = 4

Solving
-5 + 21x + 8x2 = 4

Solving for variable 'x'.

Reorder the terms:
-5 + -4 + 21x + 8x2 = 4 + -4

Combine like terms: -5 + -4 = -9
-9 + 21x + 8x2 = 4 + -4

Combine like terms: 4 + -4 = 0
-9 + 21x + 8x2 = 0

Factor a trinomial.
(-3 + -1x)(3 + -8x) = 0

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

Simplifying
-3 + -1x = 0

Solving
-3 + -1x = 0

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

Add '3' to each side of the equation.
-3 + 3 + -1x = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -1x = 0 + 3
-1x = 0 + 3

Combine like terms: 0 + 3 = 3
-1x = 3

Divide each side by '-1'.
x = -3

Simplifying
x = -3
Subproblem 2
Set the factor '(3 + -8x)' equal to zero and attempt to solve:

Simplifying
3 + -8x = 0

Solving
3 + -8x = 0

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

Add '-3' to each side of the equation.
3 + -3 + -8x = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -8x = 0 + -3
-8x = 0 + -3

Combine like terms: 0 + -3 = -3
-8x = -3

Divide each side by '-8'.
x = 0.375

Simplifying
x = 0.375
Solution
x = {-3, 0.375}