I had this problem on a test. Teacher marked the 304(t) wrong. I got the answer marked right though. I asked the teacher why I he marked 304(t) wrong, he said I shouldn't have plugged 304 in for h. I have to redo this problem and show my work. I can't figure out what I did wrong though. Could someone please explain?
thank you
After t seconds, the height of a ball thrown upward is given h(t)=-16t^2 + 80t + 240 feet. When will the ball be 304 feet high?
This is how I solved it:
304(t)=-16t^2 + 80t + 240
304t=-16t^2 + 80t + 240
-304t -304t
0=-16t^2 -224t + 240
0=-16(t^2 + 14t -15)
(t + 15)(t - 1)
t=-15 t=1
can't be -15 feet so answer is:
At 1 second, the ball will be 304 feet high.
thank you
After t seconds, the height of a ball thrown upward is given h(t)=-16t^2 + 80t + 240 feet. When will the ball be 304 feet high?
This is how I solved it:
304(t)=-16t^2 + 80t + 240
304t=-16t^2 + 80t + 240
-304t -304t
0=-16t^2 -224t + 240
0=-16(t^2 + 14t -15)
(t + 15)(t - 1)
t=-15 t=1
can't be -15 feet so answer is:
At 1 second, the ball will be 304 feet high.