Question

The position s (in feet) at time t (in seconds) of an object moving in a straight line is given by the equation
s=2t²-5t
how many seconds will it take the object to move 25 feet?

Answer 1

Assuming question is asking change in distance from t=0.
then solve for t in
\[25=2t^2-5t\]
and reject negative root.

Answer 2

we are at that point
then using quadratic formula.

Answer 3

Yes, use quadratic formula or factorize.

Answer 4

3.52?

Answer 5

or 6.02

Answer 6

The equation to solve is
\[ 2t2−5t-25=0 \]
It should give an positive integer as one of the roots.

Answer 7

so we got it wrong?

Answer 8

Did you factorize, or use the quad formula?
If you used the quad formula, watch the sign of what's inside the square-root sign.

Answer 9

we used quad formula

Answer 10

let me type it

Answer 11

\[\frac{ 5\pm \sqrt{-5^{2}-4(2)(-25)} }{ 2(2) }\]

Answer 12

Ouch!
It's \[ (-5)^2 \] instead of \[-5^2\]

Answer 13

oops i meant to put that in there

Answer 14

scanning what he did

Answer 15

Yes, if he did (-5)^2, there would be 225 in the square-root sign, and the square-root would be 15 instead of 13.2... and the integer root follows.

Answer 16

ok so 5 or 2.5

Answer 17

errr -2.5

so 5

Answer 18

Yep!

Answer 19

thank you! posted another problem he can not even figure out how to write the equation

Answer 20

You're welcome