10-6 using the quadratic formula. what is it? the quadratic formula is a method for solving...
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10-6 Using the Quadratic Formula
What is it?
The quadratic formula is a method for solving quadratic equations in the for ax2 + bx + c.
a
acbbx
2
42
Let’s try one!Solve using the quadratic
formula. 652 xx a=1, b=-5, c=6 Substitute these values into the
formula:
)1(2
)6)(1(4)5()5( 2 x
2
242525 x
2
125x
2
125x
2
125 x
2
26x
2
24x
13x 12x
Let’s try another one!Solve using the quadratic
formula. 822 xx a=1, b=-2, c=-8
)1(2
)8)(1(4)2()2( 2 x
2
3244 x
2
364x
2
64x
2
64 x
52
10x 1
2
2
x
Rewrite it…
0822 xx
Let’s try another one!Solve using the quadratic
formula. 0253 2 xx a=-3, b=5, c=-2
)3(2
)2)(3(4)5()5( 2
x
6
24255
x
6
15
x
6
15
x6
15
x
3
2
6
4
x 16
6
x
One more!Solve using the quadratic
formula. 0827 2 xx a=7, b=-2, c=-8
)7(2
)8)(7(4)2()2( 2 x
14
22442 x
14
2282x
14
10.152x
14
10.152 x
14
10.17x
22.1x 94.0x
14
10.13x
Choosing the Right Method for Solving Quadratic
EquationsThere are many methods…how to decide?The quadratic formula always works but is not
always the easiest.
Sometimes you can easily see the factors, then factoring is easiest.
Competing the square…is probably more involved than using the quadratic formula.
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