SOLUTION: graph the parabola: y= -x2-4x-4 use the quadratic formula to solve the equation to the exact value or round to two decimal places. 2x^2-x=1

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: graph the parabola: y= -x2-4x-4 use the quadratic formula to solve the equation to the exact value or round to two decimal places. 2x^2-x=1      Log On


   

Question 726857: graph the parabola: y= -x2-4x-4
use the quadratic formula to solve the equation to the exact value or round to two decimal places. 2x^2-x=1
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
graph the parabola: y=+-x%5E2-4x-4
make a table, find several points, plot them on a graph and draw a parabola through
table:
x|y
0|-4.......y=+-x%5E2-4x-4..=>..y=+-0%5E2-4%2A0-4..=>..y=+-4
1|-9.........y=+-1%5E2-4%2A1-4=-1-4-4=-9
-1|-1.........y=+-%28-1%29%5E2-4%2A%28-1%29-4=-1%2B4-4=-1
-2|0.........y=+-%28-2%29%5E2-4%2A%28-2%29-4=-4%2B8-4=0
-4|-4.........y=+-%28-4%29%5E2-4%2A%28-4%29-4=-16%2B16-4=0

2.
use the quadratic formula to solve the equation to the exact value or round to two decimal places:
+2x%5E2-x=1
+2x%5E2-x-1=0.......a=2, b=-1, and c=-1
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%2A2%2A%28-1%29+%29%29%2F%282%2A2%29+
x+=+%281+%2B-+sqrt%281%2B8+%29%29%2F4+
x+=+%281+%2B-+sqrt%289+%29%29%2F4+
x+=+%281+%2B-3%29%2F4+
solutions:
x+=+%281+%2B3%29%2F4+
x+=+4%2F4+
x+=+1
and
x+=+%281+-3%29%2F4+
x+=+-2%2F4+
x+=+-1%2F2
check it on a graph:
+graph%28+600%2C+600%2C+-5%2C+5%2C+-5%2C+5%2C++2x%5E2-x-1%29+