math functions question

[waloshin]

On question number 3 , is that a typo because I dont understand the question. If not could you give me an example on how to do it?

 

[r.j.s]

It's not a typo.

 

[waloshin]

I understand the basics:

If f(x) is = 6x+1
and g(x) is = x+9

Then find f(x) + g(x)

6x + 1 + x + 9

= 7x + 10

 

[Shaun.P]

For f(x) = g(x) let the two functions equal each other. That means 2*x^2 - x [f(x)] = 3*x + 6 [g(x)].

You need to move everyone to one side, such that it will equal 0. Simplify and factorise.
E.g:

2*x^2 - x = 3*x + 6

Move everything to the LHS:

=> 2*x^2 - 4*x - 6 = 0

Divide by common factor of 2:

=> x^2 -2*x - 3 =0

This factorises to:

=> (x-3)(x+1)=0

[Hopefully you will know how to factorise this].

=> x=3 or x=-1.

 

[jodelli]

x=3
unless I'm reading it wrong

edit: ShaunPriest got it.

 

[darklyt]

Based on ShaunPriest's answer, you're just solving for the points of intersection. If you graph the functions together, the solutions are where the graphs of the functions cross one another. (Just so you have another interpretation.)

 

[Shaun.P]

waloshin do you understand now?