Someone please help (Medals will be rewarded)
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Question

Someone please help (Medals will be rewarded)
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anonymous · Answer

attachment

anonymous · Answer

@satellite73 , @phi

anonymous · Answer

i think it might be A

nubeer · Answer

first put x = 0  and find value of y for each option.. and see for which option you get 
y =50

anonymous · Answer

I want a 100% sure answer and why ?

nubeer · Answer

tell me for which options u get y = 50?

anonymous · Answer

@nubeer is it negative or positive ?

nubeer · Answer

well just see the graph.. and see on y axis where the graph is intersecting.

anonymous · Answer

down so will that be a neg. ?

nubeer · Answer

hmm i am sorry i didn't follow u.. which value u talking of would be pos or neg?

anonymous · Answer

on the answer choice most answers are similar but before you know what one is right you have to see if its a negative or positive.

anonymous · Answer

hello ?

nubeer · Answer

hmm yes by the shpae of graph.. as it open downwards so it must be neg.

zehanz · Answer

Goes through (0,50), so +50 in the answer.
Also: (40,10) on the graph. Set x=40 and y=10 in the formulas to see which one is correct.

anonymous · Answer

b ?

anonymous · Answer

@phi am i right ?

nubeer · Answer

well the answerr is A

anonymous · Answer

are 100% positive ?

zehanz · Answer

I'd say it's A. If I check the point (40,10) is is very close.
Appearently, graph goes not quite through (40, 10). Cannot read off a point better.

anonymous · Answer

so a ?

zehanz · Answer

Ooh, there is another way of checking: it is 90 m wide, so point (45,0) is on it.

Matches perfectly with option A

anonymous · Answer

alrighty.

phi · Answer

The way to answer is notice that as x gets  big  (move to the right) the parabola is zooming down, and its y value is minus.  that means the number in front of the x^2  must be negative.

second,  when x is 0, we see that y is +50

so the answer is  negative number in front of the x^2  and +50 for the second number.

That looks like A.

We should double check that they are not fooling us ( and it the answer is NONE of these)

Let's check x=20  where the graph shows y is 40

-2/81 * 20*20 + 50 =  40.12  which is close enough.   It looks like A works.

anonymous · Answer

Thank you all so much . I wish i could give you all medals. Thanks again.

zehanz · Answer

YW!