Algebra Demystified 2nd Ed

Chapter 10 QuadratiC EQuations 357

Solve the equation by factoring.

1

2

xx^2 −+= 340

1

2

xx

xx

xx

2

2

2

340

2 1

2

3420

680

−+=

 −+







=

−+=

()

()xx−− 42 ()= 0

xx

x

−= −=

++ ++

=

40 20

44 22

4

x= 2

Solve the equation by factoring.

−− 21 xx^282 −= 80

−−−=

−− −−=−

++=

218280

218280

218280

2

2

2

xx

xx

xx

()

1

2

21828 1

2

0

9140

7

2

2

()()

     ( )(

xx

xx

xx

++=

++=

+++=20)

xx

xx

+= +=

−− −−

=−

70 20

77 22

7

==− 2

If we had multiplied both sides of the original equation by −^12 , we would
have eliminated one of the steps.

PRACTICE
Solve the equation by factoring.

1. −x^2 − x + 30 = 0


2. –9x^2 + 25 = 0


3. 0.01x^2 + 0.14x + 0.13 = 0

PRACTICE
Solve the equation by factoring.

1. −−−xxxx^22

PRACTICE
Solve the equation by factoring.