4b^2-7b-15=0

Solution for 4b^2-7b-15=0 equation:

Simplifying
4b2 + -7b + -15 = 0

Reorder the terms:
-15 + -7b + 4b2 = 0

Solving
-15 + -7b + 4b2 = 0

Solving for variable 'b'.

Factor a trinomial.
(-5 + -4b)(3 + -1b) = 0

Subproblem 1
Set the factor '(-5 + -4b)' equal to zero and attempt to solve:

Simplifying
-5 + -4b = 0

Solving
-5 + -4b = 0

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

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

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

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

Divide each side by '-4'.
b = -1.25

Simplifying
b = -1.25
Subproblem 2
Set the factor '(3 + -1b)' equal to zero and attempt to solve:

Simplifying
3 + -1b = 0

Solving
3 + -1b = 0

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

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

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

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

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

Simplifying
b = 3
Solution
b = {-1.25, 3}