# Thread: finding a and b (question must be completed by 11 o'clock tonight!!)

1. ## finding a and b (question must be completed by 11 o'clock tonight!!)

f(x)= (x^2 - 1) / (x - 1) if x<1
= ax^2 - bx + 1 if 1 <= x < 3
= 4x - a + b if x => 3

find a and b

all i know so far is that you must use a limit as x approaches 1 in the first equation to get 2

then where should i go?

2. What exactly are you asking?

$\displaystyle f(x)= \frac{x^2 - 1}{x - 1}= \frac{(x - 1)(x+1)}{x - 1} = x + 1 , x\neq 1$

3. sorry
this is what the question is

find a and b

4. Originally Posted by chris097

sorry
this is what the question is

find a and b
I suppose we're meant to assume that the question said something like "Find the values of a and b so that f(x) is continuous for all values of x" ....? Solve the following two equations simulataneously (I suggest you simplify them first):

1 + 1 = a - b + 1

a(3)^2 - b(3) + 1 = 4(3) - a + b

And since your deadline suggests that this is assignment that in all likelihood counts towards you final grade and is therefore meant to be your own work, the thread is now closed.