Help with a scenario for math

Question

thesmartone · Answer

What scenario?

anonymous · Answer

hold on im typing but thnx for coming b

anonymous · Answer

In order for Ray to decide
how much fertilizer to apply to his corn
crop this year, he reviews records from
previous years. He finds that his crop
yield y depends on the amount of fertilizer
he applies to his fields x according to the
equation y =- x^2 +4x +12

anonymous · Answer

no im stuck with this: show that iget what the scenario is saying by drawing a picture

akashdeepdeb · Answer

Is that a negative sign before x^2 ? Should that be there?

anonymous · Answer

yes

thesmartone · Answer

That is what i was wondering too ^^^

anonymous · Answer

yup the equaion is y=-x^2+4x+12

thesmartone · Answer

$$y=-x^2+4x+12$$

anonymous · Answer

yes thank u thats what i mean @TheSmartOne

thesmartone · Answer

np

thesmartone · Answer

do you have more choices?

anonymous · Answer

i know what the equation is but i need assistance wth this 
show that i get what the scenario is saying by drawing a picture

akashdeepdeb · Answer

Okay, if that is there.

Try finding the roots of the equation first.
$$-x^2 + 4x + 12 = 0$$
$$x^2 - 4x - 12 = 0$$
$$x^2 - 6x + 2x - 12 = 0$$
$$x(x-6) + 2(x-6) = 0$$
$$(x+2)(x-6) = 0$$
$$x = -2, 6$$

Also, since the sing before x is negative. The parabola is inverted. 
And since the roots are -2 and 6, it looks something like this: 

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