Solve Quadratic Equations Using the Square Root Property: example 10.3

Solve: $5 m^{2} = 80$ .

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: $2 x^{2} = 98$ .

How did it go?

The quadratic term is isolated.		$5 m^{2} = 80$
Divide by 5 to make its cofficient 1.		$\frac{5 m^{2}}{5} = \frac{80}{5}$
Simplify.		$m^{2} = 16$
Use the Square Root Property.		$m = \pm \sqrt{16}$
Simplify the radical.		$m = \pm 4$
Rewrite to show two solutions.		$m = 4, m = − 4$
Check the solutions.

The quadratic term is isolated.		$5 m^{2} = 80$
Divide by 5 to make its cofficient 1.		$\frac{5 m^{2}}{5} = \frac{80}{5}$
Simplify.		$m^{2} = 16$
Use the Square Root Property.		$m = \pm \sqrt{16}$
Simplify the radical.		$m = \pm 4$
Rewrite to show two solutions.		$m = 4, m = − 4$
Check the solutions.