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4x^2 + 10x + 3 = 0

x^2 = 3 - 4x

-4x^2 - 3x - 1 = 0

(3x + 5)^2 = 100

I know I'm suppose to use the quadratic formula for the first one (which I did, but I came up with a different answer than the choices given) but I don't know how to work the others. HELP!

2007-10-30 06:09:51 · 4 answers · asked by starscream 1 in Science & Mathematics Mathematics

4 answers

To use the quadratic formula, the equation must be in ax^2 + bx + c = 0 form.

x = (-b +/- sqrt (b^2 - 4ac)) / (2a)
so for #1,
x = (-10 +/- sqrt (10^2 - 4*4*3)) / (2*4)
= (-10 +/- sqrt (100-48) ) / 8
= (-10 +/- sqrt 52) / 8
= (-10 +/- 2 sqrt 13) / 8
= (-5 /- sqrt 13) / 4

2007-10-30 06:18:30 · answer #1 · answered by chcandles 4 · 0 0

The quadratic equation is ax^2+bx+c=0
There are 2 solutions.
x=[-b+sqrt(b^2-4ac)]/2a
x=[-b-sqrt(b^2-4ac)]/2a
4x^2+10x+3=0
a=4 b=10 c=3
x=[-10+sqrt(100-48)]/8
=[-10+7.874]/8
the other x=[-10-7.874]/8
Use the same procedure for other problems.
x^2=3-4x
x^2+4x-3=0
a=1 b=4 c=-3

(3x+5)^2=100
9x^2+30x+25=100
9x^2+30x-75=0
a=9 b=30 c=-75

2007-10-30 06:23:11 · answer #2 · answered by cidyah 7 · 0 0

4x^2 + 10x + 3 = 0
x = [-10 +/- sqrt(10^2-4(4)(3))]/(2*4)
x = [-10 +/- sqrt(52)]/8
x = [-10 +/- 2sqrt(13)]/8
x = [-5 +/- sqrt(13)]/4

x^2 = 3 - 4x
x^2 +4x -3 = 0
x = [-4 +/- sqrt(4^2-4(1)(3))]/2
x = [-4 +/- sqrt(4)]/2
x = -2 +/- 2

-4x^2 - 3x - 1 = 0
x = [3 +/- sqrt(3^2 -4(-4)(-1)]/(2* -4)
x = [3 +/- sqrt(-7))]/-8
x = [3 +/- isqrt(7)]/-8

(3x + 5)^2 = 100
3x+5 = +/- 10
3x = -5 +/- 10
x = -5(1 +/-2 )/3

2007-10-30 06:27:47 · answer #3 · answered by ironduke8159 7 · 0 0

Either factor or use the quadratic formula on all of the equations. However, you will need to rearrange the second thru fourth to look like the first.

You can do it....Sure, I knew you could.

2007-10-30 06:18:54 · answer #4 · answered by Kenneth H 3 · 0 0

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