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# Which of the following could be the equation of the graph in

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Which of the following could be the equation of the graph in [#permalink]  11 Dec 2017, 10:25
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Attachment:

xy.jpg [ 18.33 KiB | Viewed 2677 times ]

Which of the following could be the equation of the graph in the xy-plane shown above?

A. $$y = x^2 + x - 60$$

B. $$y = x^2 + x - 20$$

C. $$y = x^2 + 3x - 60$$

D. $$y = 3x^2 + x - 60$$

E. $$y = 3x^2 + 3x - 60$$
[Reveal] Spoiler: OA

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Re: Which of the following could be the equation of the graph in [#permalink]  11 Dec 2017, 17:55
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A. y = x^2 + x - 60

B. y = x^2 + x - 20

C. y = x^2 + 3x - 60

D. y = 3x^2 + x - 60

E. y = 3x^2 + 3x - 60

The parabola is in form of a a^2 + bx +c
The x-intercepts are the solutions to the equation
x1=−b−Squroot(b^2−4ac)/2a

The y-intercept is c, as y intercept means the value of y when x=0. So c = -60?
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Re: Which of the following could be the equation of the graph in [#permalink]  12 Dec 2017, 11:46
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Re: Which of the following could be the equation of the graph in [#permalink]  12 Dec 2017, 12:42
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Carcass wrote:
Attachment:
The attachment xy.jpg is no longer available

Which of the following could be the equation of the graph in the xy-plane shown above?

A. $$y = x^2 + x - 60$$

B. $$y = x^2 + x - 20$$

C. $$y = x^2 + 3x - 60$$

D. $$y = 3x^2 + x - 60$$

E. $$y = 3x^2 + 3x - 60$$

Here we have to use the vertex formula which is-

$$y = a(x-h)^2 + k$$

here h= vertex

From the graph k = -60 and h almost equal to -1

SO we need a equation as

y= (x-(-1)) -60

or y = (x + 1) -60

Only equation E have the same presentation

because $$y = 3x^2 +3x -60$$

or it can be written y = 3x(x + 1) - 60
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Re: Which of the following could be the equation of the graph in [#permalink]  14 Dec 2017, 13:50
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Thank you so much @pranab01

Regards
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Re: Which of the following could be the equation of the graph in [#permalink]  02 Nov 2018, 11:10
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Put the points (4,0) and (-4,0) to come to the solution in less time
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Re: Which of the following could be the equation of the graph in [#permalink]  16 Nov 2018, 20:52
pranab01 wrote:
Carcass wrote:
Attachment:
xy.jpg

because $$y = 3x^2 +3x -60$$

or it can be written y = 3x(x + 1) - 60

What's wrong with option (a)

can be written y= x(x+1)-60
Re: Which of the following could be the equation of the graph in   [#permalink] 16 Nov 2018, 20:52
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