SOLUTION: Hi! What are the equivalent "y"s in this quadratic function -2x^2+12x-19 using this given: x|1|2|3|4|5| i tried and get a y|-19|-3||-1|-3|-19| some said that i must have

Algebra ->  Coordinate-system -> SOLUTION: Hi! What are the equivalent "y"s in this quadratic function -2x^2+12x-19 using this given: x|1|2|3|4|5| i tried and get a y|-19|-3||-1|-3|-19| some said that i must have       Log On


   

Question 1045902: Hi! What are the equivalent "y"s in this quadratic function -2x^2+12x-19
using this given: x|1|2|3|4|5|
i tried and get a y|-19|-3||-1|-3|-19|
some said that i must have a y-intercept of
(0,19) but i dont have it.I think im wrong:(.
Answer by MathLover1(20855) About Me  (Show Source):
You can put this solution on YOUR website!

y=-2x%5E2%2B12x-19
to get y-intercept, set x=0
y=-2%2A0%5E2%2B12%2A0-19
y=-19
y-intercept is (0,-19)
to find x-intercepts set y=0
0=-2x%5E2%2B12x-19...both sides multiply by -1
0=2x%5E2-12x%2B19.........use quadratic formula

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+....in your case a=2, b=-12, and c=19

x+=+%28-%28-12%29+%2B-+sqrt%28+%28-12%29%5E2-4%2A2%2A19+%29%29%2F%282%2A2%29+

x+=+%2812+%2B-+sqrt%28+144-152+%29%29%2F4+

x+=+%2812+%2B-+sqrt%28+-8+%29%29%2F4+

x+=+%2812+%2B-+sqrt%28+-1%2A4%2A2+%29%29%2F4+

x+=+%2812+%2B-+2i%2Asqrt%28+2+%29%29%2F4+

x+=+%28cross%2812%293%2Fcross%284%29+%2B-+cross%282%29i%2Asqrt%28+2+%29%2Fcross%284%292%29+

x+=+%283+%2B-+i%2Asqrt%28+2+%29%2F2%29+

complex solutions:
x+=+3+%2B+i%2Asqrt%28+2+%29%2F2+
x+=+3+-+i%2Asqrt%28+2+%29%2F2+