Divide each term in by .

Simplify .

Cancel the common factor of .

Cancel the common factor.

Divide by .

Apply the distributive property.

Simplify the expression.

Multiply by .

Move to the left of .

Divide by .

Move to the left side of the equation by subtracting it from both sides.

Use the quadratic formula to find the solutions.

Substitute the values , , and into the quadratic formula and solve for .

Simplify the numerator.

Raise to the power of .

Multiply by .

Multiply by .

Add and .

Multiply by .

The final answer is the combination of both solutions.

The result can be shown in multiple forms.

Exact Form:

Decimal Form:

Solve for r r(r+5)(2)=90