4z^2-7z-15=0

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

Simplifying
4z2 + -7z + -15 = 0

Reorder the terms:
-15 + -7z + 4z2 = 0

Solving
-15 + -7z + 4z2 = 0

Solving for variable 'z'.

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

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

Simplifying
-5 + -4z = 0

Solving
-5 + -4z = 0

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

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

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

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

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

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

Simplifying
3 + -1z = 0

Solving
3 + -1z = 0

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

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

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

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

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

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