Question 200492
 y = -2x -7x +4
y=-9x+4
{{{ graph( 300, 200, -6, 5, -10, 10, -9x +4) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, -9x +4). 
Solution (4/9,4). 
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y=2x^2-3x-1
{{{ graph( 300, 200, -6, 5, -10, 10, 2x^2 -3x -1 ) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, 2x^2 -3x -1). 
y=-1
Using the quadratic equation {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} we get:
x=(3+-sqrt[-3^2-4*2*-1])/2*2
x=(3+-sqrt[9+8)/4
x=(3+-sqrt17)/4
x=(3+-4.123)/4
x=(3+4.123)/4
x=7.123/4
x=1.78 ans.
x=(3-4.123)/4
x=-1.123/4
x=-.28 ans.
Answer(1.78 & -.28,-1).