# Need Help On A Few Exam Review Problems

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• Dec 13th 2009, 04:37 PM
EmG
Need Help On A Few Exam Review Problems
Can anyone help me out on a few or all these problems they are the ones I am cant seem to get. =(
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58. Find a formula for a sum n for the arithmetic sequence.
$a1=-2,d=-6$

59. Find a formula for a sum n for the arithmetic sequence.
$a514,a14=50$

69. Use the Binomial Theorem to expand and simplify the expression.
$(q+5)^5$

70. Find the specified nth term in the expansion of the binomial. (write the expansion in descending powers of x.)
$(3x-2y)^8,n=5$

44. Find gºf
$f(x)=x-2,g(x)=x^2$

20. Use Descartes' Rule of Sings to determine the possible number of positive and negative zeros.
$f(x)=5x^5+10x$

13. Find the zeros of the function below algebraically, if any exist.
$f(x)=9x^3-48x^2+64x$

13. Find a third degree polynomial function of the lowest degree that has the zeros below and whose leading coefficient is one.
$2,0,6$

11. Find the zeros of the function below algebraically, if any exist.
$f(x)=x^5-26x^3+25x$

10. Describe the right-hand and the left-hand behavior of the graph.
$u(x)=-2x^4+3x^3+13$

6. Find the value(s) of x for which f(x)=g(x)
$f(x)=x^2+15x-23,g(x)=9x+4$
• Dec 13th 2009, 05:38 PM
pickslides
Hi EmG

Quote:

Originally Posted by EmG
Can anyone help me out on a few or all these problems they are the ones I am cant seem to get. =(

In future please post 1 question per thread and most importantly with your attempts on the question.

Quote:

Originally Posted by EmG
11. Find the zeros of the function below algebraically, if any exist.
$f(x)=x^5-26x^3+25x$

firstly factor out x from

$f(x)=x^5-26x^3+25x$

to give

$f(x)=x(x^4-26x^2+25)$

now whats left inside can be treated like a quadratic, make the substitution of $a = x^2$

$f(x)=x(a^2-26a+25)$

$f(x)=x(a-25)(a-1)$

$f(x)=x(x^2-25)(x^2-1)$

now using difference of 2 squares finally you get

$f(x)=x(x-5)(x+5)(x-1)(x+1)\Rightarrow x=0,1,-1,5,-5$

hope that was easy to understand.
• Dec 13th 2009, 05:44 PM
EmG
Alright will do.
• Dec 14th 2009, 03:35 AM
mr fantastic
Please don't post more than two questions in a thread. Otherwise the thread can get convoluted and difficult to follow. Start new threads as necessary for remaining questions. eg. If you have five questions, post two of them in two threads and start a new thread for the remaining one etc.

And if the question has more than two parts to it, it is best to post only that question and its parts in the thread and start a new thread for other questions.

Thread closed.