SOLUTION: Complete the square as an aid in graphing: y = x^2 + 4x - 2 After completed the square, graph the parabola. Please show all work so I can understand.

Algebra ->  Graphs -> SOLUTION: Complete the square as an aid in graphing: y = x^2 + 4x - 2 After completed the square, graph the parabola. Please show all work so I can understand.       Log On


   

Question 747569: Complete the square as an aid in graphing: y = x^2 + 4x - 2
After completed the square, graph the parabola.
Please show all work so I can understand.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Complete the square as an aid in graphing: y = x^2 + 4x - 2
Subtract 2 from both sides
x^2 + 4x + ___ = 2
Find the value that completes the square.
This is half of coefficient of x, squared, therefore 2^2 = 4, add to both sides
x^2 + 4x + 4 = 2 + 4
x^2 + 4x + 4 = 6
Which is
(x+2)^2 = 6
Find the square root of both sides
x + 2 = +/-sqrt%286%29
Two solutions
x = -2 - sqrt%286%29; about -4.45
and
x = -2 - sqrt%286%29; about +.45
:
After completed the square, graph the parabola.
we know the parabola crosses the x axis at +.45 and -4.45, looks like this
+graph%28+300%2C+200%2C+-6%2C+5%2C+-10%2C+10%2C+x%5E2%2B4x-2%29+