Question 747569
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(6)}}}
Two solutions
x = -2 - {{{sqrt(6)}}}; about -4.45
and
x = -2 - {{{sqrt(6)}}}; 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( 300, 200, -6, 5, -10, 10, x^2+4x-2) }}}