Mathematics
OpenStudy (anonymous):

NEED HELP! THE QUESTION IS BELOW:)

OpenStudy (anonymous):

Which equation matches the graph shown below? y = 8x² + 2x – 5 y = 8x² + 2x + 5 y = 2x² + 8x + 5 y = 2x² + 8x – 5

OpenStudy (anonymous):
OpenStudy (anonymous):

when you put x=0 you will get y=-5 so you two choices

OpenStudy (ash2326):

Just 5 minutes

OpenStudy (anonymous):

you need to use discrimanant

OpenStudy (ash2326):

Sorry, kept you waiting

OpenStudy (anonymous):

its cool

OpenStudy (anonymous):

you cannot solve by looking at the graph, because x-intercets arent clear or exact value..

OpenStudy (anonymous):

this is the answer 2x² + 8x – 5

OpenStudy (anonymous):

thanks..

OpenStudy (ash2326):

We are given 4 options Let's see the graph , when x =0 y is around -5 so Let's put x =0 in each and check -5 5 5 -5 either it's a or d

OpenStudy (anonymous):

here is y=0 x values.. http://www.wolframalpha.com/input/?i=solve+2x%C2%B2+%2B+8x+%E2%80%93+5%3D0

OpenStudy (ash2326):

Now Let's write this in vertex form A parabola with vertex h, k is given as \[y=a(x-h)^2+k\] we have option a y=8x^2+2x-5 Let's try to convert this in standard form \[y=8(x^2+x/4+1/64)-1/8-5\] or \[y=8(x+1/8)^2-41/8\] so here vertex is -1/8, -41/8 Now option d \[y=2x^2+8x-5\] or \[y=2(x^2+4x+4)-8-5\] or \[y=2(x+2)^2-13\] here vertex is (-2, -13) In our graph also the vertex is (-2, -13) so option D is the answer

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