SOLUTION: Given that {{{ f(x)=3x^2-7x+1 }}} find f(-1) find f(x+1) find f(x+h) I have spent a lot of time on these problems, and I must be missing something because I cannot get them r

Algebra ->  Rational-functions -> SOLUTION: Given that {{{ f(x)=3x^2-7x+1 }}} find f(-1) find f(x+1) find f(x+h) I have spent a lot of time on these problems, and I must be missing something because I cannot get them r      Log On


   

Question 273823: Given that +f%28x%29=3x%5E2-7x%2B1+
find f(-1)
find f(x+1)
find f(x+h)
I have spent a lot of time on these problems, and I must be missing something because I cannot get them right.
My answer for the second one was +3x%5E2-7x%2B11+
for the third one was +3x%5E2%2B3h%5E2-7x%2B1+
My answer for the first was the most confusing of all, depending on whether I entered it entirely into my calculator, and if I broke the problem into segments ( +3%28-1%29%5E2-7%28-1%29%2B1+ vs 3-7%2B1 my answer changed. The first was 11, the second was -3.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
# 1



f%28x%29=3x%5E2-7x%2B1 Start with the given equation.


f%28-1%29=3%28-1%29%5E2-7%28-1%29%2B1 Plug in x=-1.


f%28-1%29=3%281%29-7%28-1%29%2B1 Square -1 to get 1.


f%28-1%29=3-7%28-1%29%2B1 Multiply 3 and 1 to get 3.


f%28-1%29=3%2B7%2B1 Multiply -7 and -1 to get 7.


f%28-1%29=11 Combine like terms.


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# 2

f%28x%29=3x%5E2-7x%2B1 Start with the given equation.


f%28x%2B1%29=3%28x%2B1%29%5E2-7%28x%2B1%29%2B1 Replace each 'x' with 'x+1'.


f%28x%2B1%29=3%28x%5E2%2B2x%2B1%29-7%28x%2B1%29%2B1 FOIL


f%28x%2B1%29=3x%5E2%2B6x%2B3-7x-7%2B1 Distribute


f%28x%2B1%29=3x%5E2-x-3 Combine like terms.


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# 3

f%28x%29=3x%5E2-7x%2B1 Start with the given equation.


f%28x%2Bh%29=3%28x%2Bh%29%5E2-7%28x%2Bh%29%2B1 Replace each 'x' with 'x+h'.


f%28x%2Bh%29=3%28x%5E2%2B2xh%2Bh%5E2%29-7%28x%2Bh%29%2B1 FOIL


f%28x%2Bh%29=3x%5E2%2B6xh%2B3h%5E2-7x-7h%2B1 Distribute