Solve Quadratic Equations Using the Quadratic Formula: example 10.35

Solve $4 x^{2} - 20 x = −25$ by using the Quadratic Formula.

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Solve $r^{2} + 10 r + 25 = 0$ by using the Quadratic Formula.

How did it go?


Add 25 to get the equation in standard form.
Identify the a, b, c values.
Write the Quadratic Formula.
Then substitute in the values of a, b, c.
Simplify.
Simplify the radical.
Simplify the fraction.
Check. We leave the check to you.


Add 25 to get the equation in standard form.
Identify the a, b, c values.
Write the Quadratic Formula.
Then substitute in the values of a, b, c.
Simplify.
Simplify the radical.
Simplify the fraction.
Check. We leave the check to you.