-b^2-4(2)(-9)=

Solution for -b^2-4(2)(-9)= equation:

Simplifying
-1b2 + -4(2)(-9) = 0

Multiply -4 * 2
-1b2 + -8 * -9 = 0

Multiply -8 * -9
-1b2 + 72 = 0

Reorder the terms:
72 + -1b2 = 0

Solving
72 + -1b2 = 0

Solving for variable 'b'.

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

Add '-72' to each side of the equation.
72 + -72 + -1b2 = 0 + -72

Combine like terms: 72 + -72 = 0
0 + -1b2 = 0 + -72
-1b2 = 0 + -72

Combine like terms: 0 + -72 = -72
-1b2 = -72

Divide each side by '-1'.
b2 = 72

Simplifying
b2 = 72

Take the square root of each side:
b = {-8.485281374, 8.485281374}