CPM Homework Help : INT3 Problem 1-19

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1-19.

Solve each of the following quadratic equations. If you need help, refer to the Math Notes box in this lesson.

$x^2-8x+15=0$
Method 1 (a):
Factor.
$(x−5)(x−3)=0$
Answer (a):
Use the Zero Product Property:
$(x−5)=0\ \ \ \ (x−3)=0$
$x=5\ \ \ \ \ \ x=3$
Method 2 (a):
Use the Quadratic Formula.
$x=\frac{-(-8)\pm\sqrt{(-8)^2-4(1)(15)}}{2(1)}$
Answer Method 2 (a):
$x=\frac{8\pm2}{2}$
$x=5,\,\,\,x=3$

$2x^2-5x-6=0$
Hint (b):
Notice if you try to factor $2x^2−5x−6$ , it doesn't work. Use the Quadratic Formula when that happens.
Answer (b):
$x=\frac{5\pm\sqrt{73}}{4}$
$x\approx3.39,\ x\approx-0.89$

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