Algebra Demystified 2nd Ed

Chapter 10 QuadratiC EQuations 371

4. 2x^2 = 9


5. –3x^2 + 4x + 1 = 0


6. 9x^2 – x = 10


7. 10x^2 – 5x = 0


8. 01 ..xx^2 –  0111   –  =  0
   9.^1
   3

1

6

1

8

xx^2  + – =  0

10. 80x^2 – 16x – 32 = 0


11. 18x^2 + 39x + 20 = 0


12. x^2 + 10x + 25 = 0

✔SOLUTIONS

1. xx

x

(^2530)
(^55452512)
2
51
−+=
=−− ±−−()() (1)(3)= ±−= ±
2(1)
(^233)
2

2. 460

(^114461196197)
2
2
xx
x
+−=
=−± −−()()=−± −− =−±
2(4)
()
8 88

3. 732320
   3347 2

22

2

xx xx

x

+= +−=

=−± −−

(Equivalentto7

)(

)

( ))

2(7)

=−± −−^39 ()^56 =−±

14

365

14

4. 29 290
   04

22

2

xx

x

=−=

=−± −−=

(Equivalentto)

0(2)(9)

2(2)

0072

4

72

4

36 2

4

62

4

32

2

±−− =± =±⋅

=± =±

()

5. −++=

=−± −−

−

=−± −−

−

=

3410

4443

3

41612

6

2

2

xx

x ( )(1)

2( )

() 4428

6

447

6

427

6

727

3

±

−

=−± ⋅

−

=−±

−

=−±

−

2(2)= ±

6