3. A model rocket is launched from a roof into a field. The path rocket can be modleed by the equation.
y=-0.04x^2+8.3x+4.3, where x is the horizontal distance, in meters, from the starting point on the roof and the y is the height, in meters, of the rocket above the ground. How far horizontally from its strating point will the rocket land? Round to the nearest 100th meter.
A- 208.02m
B-416.03m
C-0.52m
D-208.19m

Question

3. A model rocket is launched from a roof into a field. The path rocket can be modleed by the equation.
y=-0.04x^2+8.3x+4.3, where x is the horizontal distance, in meters, from the starting point on the roof and the y is the height, in meters, of the rocket above the ground. How far horizontally from its strating point will the rocket land? Round to the nearest 100th meter.
A- 208.02m
B-416.03m
C-0.52m
D-208.19m

ranga · Answer

When the rocket lands, the height of the rocket above the ground will equal zero.
Set y = 0 and solve the quadratic equation for x.

phebe · Answer

so is it C

ranga · Answer

I cannot give out the answer.  You have to show the work how you got C.

phebe · Answer

well im guessing

phebe · Answer

no its D k

ranga · Answer

-0.04x^2 + 8.3x + 4.3 = 0
Divide throughout by -0.04
Then solve the quadratic equation.  
Or you can directly use the quadratic formula and solve for x.
$$\Large x = \frac{ -b \pm \sqrt{b ^{2} - 4ac} }{ 2a }$$

phebe · Answer

so i divide

phebe · Answer

i got d well i was told D is tha rit

ranga · Answer

$$\Large x = \frac{ -8.3 \pm \sqrt{(8.3) ^{2} - 4(-0.04)(4.3)} }{ 2(-0.04) } = ?$$

phebe · Answer

hold on k let me put that in my calculater k

phebe · Answer

um.... can u jus giv me the answer i don't get it

ranga · Answer

I will get a warning from the moderator if I just give out the answer.  But you should be able to do the above calculation.  Quadratic equation occurs often in math and it is better to learn to solve it so you don't have to ask someone each time.

phebe · Answer

ok i'll try but nvm i'll close this question so i can put another up k

ranga · Answer

alright.

phebe · Answer

can u help me with that one

anonymous · Answer

well you need to let y = 0  that means the reockat has no height, and solve for x

easiest way seems to be the general quadratic formula 

x=−8.3±8.32−4×−0.04×4.3−−−−−−−−−−−−−−−−−−−√2×−0.04

phebe · Answer

thanx

anonymous · Answer

no problem :)

phebe · Answer

but im going to close the question k

anonymous · Answer

ok

phebe · Answer

u think u can help me wit the next one i puit up

anonymous · Answer

sure

anonymous · Answer

wait are you from mulberry middle?

phebe · Answer

no where is that

phebe · Answer

message me anyway k

anonymous · Answer

haha sorry my collage is next to it and i know a girl named phebe.

anonymous · Answer

ok