hiii im 13 and im not very smart i have been given this formular which i dont get this is it:
The equation 3x2 - 3x = 45 has a solution between 4 and 5.
i dont think it is possible but plz help as this homework is due tommoro
thnaks
love helllp me

2. ## Re: please help me on this algebreic formular

Originally Posted by helppppp
hiii im 13 and im not very smart i have been given this formular which i dont get this is it:
The equation 3x2 - 3x = 45 has a solution between 4 and 5.
i dont think it is possible but plz help as this homework is due tommoro
I assume that you meant to write $\displaystyle 3x^2 - 3x = 45?$

$\displaystyle 3x^2 - 3x = 45$

$\displaystyle \Rightarrow3x^2 - 3x - 45 = 0$

Factor out the greatest common factor, and then factor the remaining trinomial.

3. ## Re: please help me on this algebreic formular

If you want to prove that it has a solution between 4 and 5, move everything to one side:

$\displaystyle 3x^2 - 3x - 45 = 0$

If x = 4, $\displaystyle 3x^2 - 3x - 45 = -9$, and if x = 5, $\displaystyle 3x^2 - 3x - 45 = 15$. The function is continuous everywhere, so by the intermediate value theorem, there must be a real root between 4 and 5. You can use the quadratic formula to find that root.