Tuesday, November 24, 2015

Need help solving: x(2x+7)=0 & 9x squared + 12x +14 (the answer is a fraction)I do not understand factoring the quadratic equation when the...

We'll solve the first
equation:


x(2x+7) = 0


The
product is cancelling if one of the factors is
cancelling.


We'll cancel out the first factor,
x:


x = 0


We'll cancel out the
next factor, x:


2x+  7 = 0


2x
= -7 =>> x = -7/2


We'll solve the second
equation


9x^2 + 12x + 14 =
0


We'll apply quadratic formula to determine it's
roots::


x1 =
[-b+sqrt(b^2-4ac)]/2a


We'll identify he coefficients
a,b,c.


a = 9, b = 12 and c =
14


x1 = [-12+sqrt(144 -
504)]/18


x1 =
[-12+sqrt(-360)]/18


x1 =
(-12+6i*sqrt10)/18


We'll divide by
6:


x1 = (-2+i*sqrt10)/3


x2 =
(-2-i*sqrt10)/3


The real roots of the 1st
equation are x = 0 and x = -7/2 and the roots of the 2nd equation are complex number and
they are x1 = (-2+i*sqrt10)/3 and x2 =
(-2-i*sqrt10)/3.

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