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Mathematics 8 Online
OpenStudy (anonymous):

The parabola is a graph of a quadratic equation. What are the roots of the equation?

OpenStudy (anonymous):

OpenStudy (amistre64):

without knowing the rule of f(x), approximate the x intercepts the best you can

OpenStudy (anonymous):

(2,3)

OpenStudy (amistre64):

or, if the graph is accurate enough, i see a vertex and a y intercept that can be culled to create a suitable equation from

OpenStudy (amistre64):

vertex at -7,3 y = m(x+7)^2 + 3 at x=0, y = 2 2 = m(7)^2 + 3 -1 = 49m m = -1/49

OpenStudy (amistre64):

lol, got that a little out of place

OpenStudy (amistre64):

vertex is 3,-7 ....

OpenStudy (anonymous):

okay..

OpenStudy (amistre64):

vertex at 3,-7 y = m(x-3)^2 -7 at x=0, y = 2 2 = m(-3)^2 - 7 9 = 9m m = 1

OpenStudy (anonymous):

im trying to follow you lol

OpenStudy (amistre64):

y = (x-3)^2 - 7 can be solved for y=0 0 = (x-3)^2 - 7 7 = (x-3)^2 +- sqrt(7) = x-3 3 +- sqrt(7) = x

OpenStudy (anonymous):

okay.. now what

OpenStudy (amistre64):

ok ... show me where this goes awry for you ....

OpenStudy (anonymous):

wait what

OpenStudy (amistre64):

i assume since i got to the end of it and you are still lost that there must be some place that threw you for a loop; so instead of me doing all the work for you, tell me where this starts to not make sense ....

OpenStudy (anonymous):

at this part 0 = (x-3)^2 - 7 7 = (x-3)^2 +- sqrt(7) = x-3 3 +- sqrt(7) = x

OpenStudy (amistre64):

thats just solving for y=0; which is how the roots (or zeros) are defined

OpenStudy (anonymous):

okay so the answer is (0,3) ??

OpenStudy (amistre64):

do you understand how i got the equation? y = (x-3)^2 - 7 ?

OpenStudy (anonymous):

not really lol

OpenStudy (anonymous):

sorry im stupid :/ lol

OpenStudy (amistre64):

your material should have what is called the "vertex" form of a quadratic equation ... show me what it looks like in its general form

OpenStudy (anonymous):

y = a(x – h)2 + k

OpenStudy (amistre64):

good, and (h,k) is the point that defines the vertex; what is the point for the vertex on the given graph?

OpenStudy (anonymous):

(0,3) ?

OpenStudy (amistre64):

not quite .. the vertex is the bend in the graph where it start to go back on itself; it changes directions

OpenStudy (anonymous):

-7,3 ?

OpenStudy (amistre64):

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