370 alGEbra De mystif ieD
Solve the quadratic equation with the quadratic formula.1
3xx^2 +−= 20We begin by multiplying both sides of the equation by 3 to eliminate the
fraction.31
3 xx (^2) +− 230
= ()
x^2 + 3 x − 6 = 0 a = 1 b = 3 c=− 6
x=−± −−^33416 =−± −− =−± =−+
21
3924
2
333
2
333
2
(^2) ()()
()
() ,−−− 333
2
Solve the quadratic equation with the quadratic formula.
01 ..xx^2 −+ 08 02. 10 =^
We can eliminate the decimal numbers by multiplying both sides of the
equation by 100.
100(0.1x^2 – 0.8x + 0.21) = 100(0)
10 x^2 – 80x + 21 = 0 a = 10 b = – 80 c = 21
x () ()()( )
()
= −−^80 ± −−^8041021 = ^ ± −
210
(^28064008840)
20
80 5560
20
80 4 1390
20
80 2 139
= ±
= ± = ±
⋅ 00
20
240 1390
20
40 1390
10
40 1390
1
= ± = ±
= +
( )
00
40 1390
10
, −
PRACTICE
Solve the quadratic equation with the quadratic formula.
- x^2 – 5x + 3 = 0
- 4x^2 + x – 6 = 0
- 7x^2 + 3x = 2
PRACTICE
Solve the quadratic equation with the quadratic formula.- xxx^22 – 5
PRACTICE
Solve the quadratic equation with the quadratic formula.