• Aug 27th 2009, 02:22 PM
yitsongg
http://www.montgomeryschoolsmd.org/S.../PreCalc09.pdf

My answers to questions 25 to 30

25 3y+2/3y-2
26 .1873543715
27. -52
28. x=3
29. 244140625
30. -32768(x^2y^4)
• Aug 27th 2009, 02:27 PM
RobLikesBrunch
Quote:

Originally Posted by yitsongg
http://www.montgomeryschoolsmd.org/S.../PreCalc09.pdf

My answers to questions 25 to 30

25 3y+2/3y-2 Correct
26 .1873543715 Incorrect
27. -52 Correct
28. x=3 Correct, although it isn't x=3, but simply 3.
29. 244140625 Incorrect
30. -32768(x^2*y^4) Correct

26 is incorrect because it is a decimal approximation. When asked to simplify, you are almost always expected to give your answers exactly (i.e. not simply plug the numbers into your calculator, but rather manipulate them by hand to get a more "simple" number. You shouldn't use a calculator at all). Given that you were able to do the other problems, I assume you can do 26 by yourself. Once you have the correct answer, re-post it and I'll check it for you.
• Aug 27th 2009, 03:20 PM
yitsongg
26. (3- 2)(2 3+5
29. 125

spaces mean breaket
• Aug 27th 2009, 03:46 PM
RobLikesBrunch
Quote:

Originally Posted by yitsongg
26. (3- 2)(2 3+5 Incorrect
29. 125 Correct

spaces mean breaket

For 26, I assume they simply don't want the square root in the denominator (it's a bit of a pedantic simplification). So:

$\frac{3-\sqrt{2}}{2\sqrt{3}+5} \cdot \frac{2\sqrt{3}-5}{2\sqrt{3}-5}$ (We multiply the fraction by the conjugate of the denominator over the conjugate so we can get rid of the square root, and not get a middle term in our multiplication because the -5 and the +5 will result in a cancellation once multiplied out)

$\frac{(3-\sqrt{2})(2\sqrt{3}-5)}{-13} = \frac{(\sqrt{2}-3)(2\sqrt{3}-5)}{13}$

P.S. I apologize for saying 29 was incorrect for the wrong reason before. I hadn't looked at the question, and I misread it as an approximate decimal. But, it's correct now.