Question 1098025: I have the following polynomial function and I'm trying to find the y-intercept:
S(x) = 1/2(x-1)^3+4
I set x to zero and proceeded this way:
(0-1) = -1
(-1)^3 = -1
1/2(-1) = -1/2 (or -0.5)
-0.5 + 4 = 3.5
so y=3.5
Unfortunately, the answer my textbook gives for the y-intercept is -1. I have no idea where I'm going wrong. Also, I tried transforming the graph from the parent function y=x^3, so I moved it right one unit and up 4 units (I didn't get as far as compressing it vertically by a factor of 1/2) and I can't figure out how to get it to cross the y-axis at -1, let alone 3.5. I am so confused! I'd appreciate whatever help you can give me. Thanks!
Answer by ikleyn(52776)   (Show Source):
You can put this solution on YOUR website! .
Your steps, your calculations and your answer are PERFECTLY correct.
Their answer is wrong.
Actually, their answer "-1" fits for x-intercept.
So, it looks like the error is on their side.
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comment from student. I'm sorry to be a pest, but in my previous response to you, I mentioned that I couldn't figure out
how to calculate -1 as the x-intercept for the above polynomial function: S(x)= 1/2(x-1)^3 +4. So this is what I just tried:
1/2(x-1)^3 +4 = 0 ---> 1/2(x-1)^3 = -4 ---> (x-1)^3 = -8 x-1 = cube root negative 8 (I don't have the symbols for that; sorry)
x-1 = -2 ---> x = -2 +1 ---> x = -1
Is this correct? Again, let me know if it's improper for me to be asking you more questions via email this way,
and I will re-submit this as another question on algebra.com. Thank you.
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My response. 1. Your calculations in your comment are correct.
2. It is preferable if you will post your other questions on algebra.com.
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