Posted by **HM** on Thursday, September 29, 2011 at 11:28am.

Another question which is confusing.

The position of an object moving in a straight line is give by s=2t^2-3t, where is s in metres and t is the time in seconds the object has been in motion..

how long will it is take the object to move 6 meters?

I first used the simplfying rule but it did not work.. Then I used the vertex formula and I got a 2.5 from which I got a negative number..

Moreover then I used the quadratic formula and I got a 2.6 which I put in the formula of 2t^2-3t and I got a 5.7

Where am I going wrong?

The true answer is 2.6 seconds.

- College Math -
**bobpursley**, Thursday, September 29, 2011 at 12:01pm
s=2t^2-3t

2t^2-3t-6=0

t= (3+-sqrt(9+48))/4=3/4 +-(sqrt57)/4

in my head t= .75+-7.5/4=.75+-about 1.8

= about 2.6seconds So recheck your quadratic formula solution

- College Math -
**HM**, Thursday, September 29, 2011 at 12:12pm
Aha, how silly of me!

My answer were absolutely correct, which was 2.6.. I don't know what urged me to go ahead and put it in the formula again..

Thank you for reconfirming my stupidity.

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