# Thread: Need help on Function Assignment :P

1. ## Need help on Function Assignment :P

Hello! I need help with some questions I have to do. Any help would be much appreciated.

A) Determine the inverse of y= 5x21-3x-4

I got the answer:

log2(x+4/5)-1 = y
-3

That doesn't seem right to me. :/

B) What are the intercepts of; y= (x-a)2(x+2a) ; a>0

I got to y= (x3+2ax2)-(a2x-2a3)

Not sure what to do now...

C) This is a weird one. :/ Explain how a relation could be restricted to a function.

Da fuq??? O_o

D) What transformations have been made to j(x) to get 2j(1-x)?

Would that be; dilated vertically by 2, translated 1 upwards, and reflected in the x-axis???

E) The Function,Point, and Asymptote of; ~ f1(x)=log2x; (1,0); x=0; ~ when it is translated four units left, and one unit up???

Any help with any of the questions would be beyond fantastic!

2. ## Re: Need help on Function Assignment :P

Originally Posted by ShootMePlease
Hello! I need help with some questions I have to do. Any help would be much appreciated.

A) Determine the inverse of y= 5x21-3x-4

I got the answer:

log2(x+4/5)-1 = y
-3

That doesn't seem right to me. :/

B) What are the intercepts of; y= (x-a)2(x+2a) ; a>0

I got to y= (x3+2ax2)-(a2x-2a3)

Not sure what to do now...

C) This is a weird one. :/ Explain how a relation could be restricted to a function.

Da fuq??? O_o

D) What transformations have been made to j(x) to get 2j(1-x)?

Would that be; dilated vertically by 2, translated 1 upwards, and reflected in the x-axis???

E) The Function,Point, and Asymptote of; ~ f1(x)=log2x; (1,0); x=0; ~ when it is translated four units left, and one unit up???

Any help with any of the questions would be beyond fantastic!
Before even trying to help, I need to point out that you should not use x to represent both a multiplication symbol and the letter x. How am I supposed to tell them apart? Use brackets or a dot for the multiplication.

Also, you must use brackets in the correct places, since x + 4/5 is \displaystyle \begin{align*} x + \frac{4}{5} \end{align*}, while (x + 4)/5 is \displaystyle \begin{align*} \frac{x + 4}{5} \end{align*}

Assuming that you had made these changes, part A would be correct. Why don't you think it's right?

For B, why are you expanding (incorrectly btw)? To find x intercepts, let y = 0. To find y intercepts, let x = 0.

Since it's already factorised you can apply the null factor law once you have let y = 0.

For C, first of all we don't like swearing, even if it is censored. Then, what do you know about functions? Do you understand that a function is a mapping of two numbers, and works like a computer program, with numbers going in (the Independent Variable, usually x), and each number going in getting a number coming out (the Dependent Variable, usually y)? Therefore, a relation can only be a function if each number going in only has ONE possible value coming out. What could you do if your function is giving you multiple values for the Dependent Variable for particular values of the Independent Variable?

For D, you are almost correct. It's actually translated 1 to the left, not 1 upward.

For E, how can you write that function to take into account its transformations?