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# Math help!

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The graph of a certain quadratic \(y = ax^2 + bx + c\)  is a parabola with vertex \( (-4,0)\)  which passes through the point (1,-75). What is the value of a?

tertre  Mar 12, 2017

#1
+5

Im not sure if this is right or not but I had a go:

y=ax2+bx+c

use vertex/turning point form

y=a(x-h)2+k

sub in vertex

y=a(x+4)2

sub in point values and solve for a

-75=a(1+4)2

-75=25a

a=-3

Hope this helps.

Guest Mar 12, 2017
edited by Guest  Mar 12, 2017
Sort:

#1
+5

Im not sure if this is right or not but I had a go:

y=ax2+bx+c

use vertex/turning point form

y=a(x-h)2+k

sub in vertex

y=a(x+4)2

sub in point values and solve for a

-75=a(1+4)2

-75=25a

a=-3

Hope this helps.

Guest Mar 12, 2017
edited by Guest  Mar 12, 2017
#2
+1166
+5

That is correct!

tertre  Mar 12, 2017

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