SOLUTION: Hello, I am trying to solve quadratic equations by graphing, I have been looking at the example of the book and makes no sence to me. the problem is asking me to use a graph to

Algebra ->  Linear-equations -> SOLUTION: Hello, I am trying to solve quadratic equations by graphing, I have been looking at the example of the book and makes no sence to me. the problem is asking me to use a graph to       Log On


   

Question 308536: Hello,
I am trying to solve quadratic equations by graphing, I have been looking at the example of the book and makes no sence to me.
the problem is asking me to use a graph to estimate the solutions of the equation, and to check my solutions algebraically.
+-4x%5E2-8x=12+
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
use a graph to estimate the solutions of the equation, and to check my solutions algebraically.
-4x^2-8x=12
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Divide thru by -4 to simplify the equation.
---
x^2 + 2x = -3
---
Graph the two equations
y = x^2+2x
and
y = -3
-------------------
graph%28400%2C300%2C-10%2C10%2C-10%2C10%2Cx%5E2%2B2x%2C-3%29
-------------------
Find the points of intersection of the two graphs.
Note: The graphs do not intersect; there is no Real
Number solutions for the problem.
================================
Solving analytically:
x^2 + 2x +3 = 0
x = [-2 +- sqrt(4 -4*3)]/2
---
x = [-2 +- sqrt(-8)]/2
x = [-2 +-2isqrt(2)]/2
---
x = [-1 +- isqrt(2)]
----
Note: These solutions are complex numbers.
==============================================
Cheers,
Stan H.