Math help pleasee, polynomials !
Favorites|Homepage
Subscriptions | sitemap
HOME > Mathematics > Math help pleasee, polynomials !

Math help pleasee, polynomials !

[From: ] [author: ] [Date: 11-10-30] [Hit: ]
.therefore.........
I cant get this question right :(

You can estimate the height, h , in meters of a toy rocket at any time, t in seconds during its flight. Use the formula h= -5t squared + 23t +10. Write the formula in factored form. Then calculate the height of the rocket 3s after it is launched.

-
ok so first part of the question is telling you to factorise the equation that you're already given:

h= -5t^2 +23t +10
h= (-5t - 2)x(t-5)
you can take aout a factor of -1:

h= -(5t -2)x(t-5)

Because mathematicians are lazy, they don't put the 'x' for multiplicatin and just assume that you'll know the brackets are to be multiplied by each other:

h= -(5t -2)x(t-5)

Now this is true - you can expand the brackets and see that you'll get back to the original equation. But how did I get the answer? Well, you know that you'll need brackets with 't' in one and '-5t' in the other because when you multiply these, you get -5x^2 which is in the equation. The other terms, well it's kinda like trial and error - but with a lot of practice you'll just know what numbers should go in.

Now, you've got the equation for h, so if you substitute t=3 (time in seconds which the question is asking you to find the height at), you'd get the height in metres:

h= -( (5x3) +2) (3-5)
h = - (15 +2) x -2
h= -17 x -2
h= 34 m

Hope that makes sense :)

-
h=-5t^2+23t+10
factor this out
multiply-5t^2*10 and find the products that add up to 23t

-5t^2+25t-2t+10
find the common factors of each pair.. put the factor outside the bracket and divide each term inside the bracket by the factor
5t(-5t^2/5t +25t/5t) +2(-2t/2 +10/2)
5t(-t+5)+2(-t+5)
do the same as above here except that the common facot is (-t+5) or -(t-5)
-(t-5)(5t+2)


h=-(t-5)(5t+2)

therefore... h=-(3-5)(5(3)+2)

h= -(-2)(17)
h=34m
1
keywords: pleasee,polynomials,help,Math,Math help pleasee, polynomials !
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .