what am i doing wrong? find the average velocity of the object from interval from t=1 to the time .5 seconds later? s(t)=20-5t^2.
I did: [S(.5)-S(1)]/ -.5 ----7.5. but answer is -12.5???

Question

what am i doing wrong? find the average velocity of the object from interval from t=1 to the time .5 seconds later? s(t)=20-5t^2. 
I did: [S(.5)-S(1)]/ -.5 --->-7.5. but answer is -12.5???

amistre64 · Answer

s(t) is position usually

amistre64 · Answer

but thats beside the point

amistre64 · Answer

S(1) - S(.5)     (20-5)-(20-.25)
--------- =  --------------  right?
   1 - .5                    .5

anonymous · Answer

i did 18.75-15 but anyway it doesnt get anywhere near 12.5

amistre64 · Answer

well, 1 to 1.5 is what is asking if i read it right lol

anonymous · Answer

ooohhhhhh okay i got it

amistre64 · Answer

S(1.5) - S(1)     (20-2.25)-(20-5)
---------- =  ---------------  maybe lol
   1.5 - 1                    .5

anonymous · Answer

yea instead of .5 i should have put 1.5. thanksss

amistre64 · Answer

yep; and i dropped a "5" for some reason.  should be 5(2.25) up there