Help me with these math problems!

Test Preparation SAT Preparation
1

<p>I got these wrong/guessed and I did not know why it is correct. Can anyone explain them to me? Thanks!</p>

<p><a href="http://i.imgur.com/OQMuh.png%5B/url%5D"&gt;http://i.imgur.com/OQMuh.png&lt;/a>
Answer is E.</p>

<p><a href="http://i.imgur.com/c6agh.png%5B/url%5D"&gt;http://i.imgur.com/c6agh.png&lt;/a>
Answer is D.</p>

<p><a href="http://i.imgur.com/qNOL7.png%5B/url%5D"&gt;http://i.imgur.com/qNOL7.png&lt;/a>
Answer is A (really do not know this one).</p>

<p><a href="http://i.imgur.com/Nnfgb.png%5B/url%5D"&gt;http://i.imgur.com/Nnfgb.png&lt;/a>
Answer is 125.</p>

<p><a href="http://i.imgur.com/QQKv6.png%5B/url%5D"&gt;http://i.imgur.com/QQKv6.png&lt;/a>
Answer is D.</p>

<p>Thanks!</p>

2

<p>I should be studying for finals right now but I’ll help you with the first one :stuck_out_tongue:
The way you should approach this one is:
r+p=5</p>

<h2>r-p=2</h2>

<p>2r=7
r=7/2
Plug r back in.
p=3/2</p>

<p>r/p (2’s cancel) = 7/3</p>

3

<p>i could answe rthe middle one. there’s a rule in geometry that the third side cant be more than the sum of the other twoo sides . </p>

<p>so it’s A. </p>

<hr>

<p>cmon smart CC’ers answer those other questions, i don’t get them and want to learn them too!!!</p>

4

<p>oh! i think i got the last one. i think u can plug #'s in for xy and backsolve that way. if the number that represnts xy multiplied by 35 can be square-rooted to an intiger than it’s right</p>

5

<p>1)</p>

<p>In equations involving fractions on the SAT, the numerator of one side is always algebraically equal to the numerator on the other; same applies to the denominator.</p>

<p>Split up the numerators and denominators into two separate equations:</p>

<p>r + t = 5 ---- (1)
r - t = 2 ---- (2)</p>

<p>(1) + (2) gives you,</p>

<p>2r + t - t = 5 + 2
2r = 7
r = 3.5</p>

<p>Substitute the value of r in either (1) or (2) and you get t = 1.5</p>

<p>t/r = 3.5/1.5 = 7/3</p>

<p>2)</p>

<p>You have the coordinates of two points given to you and the equation of the line. Substitute the y-coordinate of the points in the equation and find p and t.</p>

<p>For the first point:</p>

<p>x = p
y = 5</p>

<p>Substitute in the equation:</p>

<p>5 = p^2 + 9
p^2 = 4
p = 2</p>

<p>Repeat this step for the second point and you get t = 4.</p>

<p>Now, the equation to find the slope of the line is: (y2 - y1)/(x2 - x1) where (x1, y1) and (x2, y2) are the coordinates of any two points on the line. </p>

<p>Using the formula you get slope = -6.</p>

<p>3)</p>

<p>Is it regarding a triangle? If so, then there is a rule that states that the sum of two sides is always greater than the third side. AC must be 10.</p>

<p>I have to go now; will get back to you later on the last two if no one else will :)</p>

6

<p>For the fifth one, starting with choice (C), multiply each answer choice by 35, and then take the square root in your calculator. If you get an integer, then you have found the answer. If you get an answer with a decimal point, eliminate that answer choice.</p>

7

<p>For the third one, use the triangle rule. This says that the third side of a triangle is strictly between the difference and sum of the other two sides. So, in this case the third side is between 1 and 11, inclusive (inclusive because in this question we can have a straight line). The answer is thus (A).</p>

<p>Make sure you know the triangle rule. It always shows up on “hard” questions, but if you know the rule, these questions are quite easy.</p>

8

<p>Another way to do the first one is to use the answer choices as a “guide” to guess and check. (A), (C) and (E) hint at the fact that you may want to use 7 and 3. Letting r=7 and t = 3 gives the answer:</p>

<p>(7+3)/(7-3)=10/4=5/2 which is what we want.</p>

<p>So the answer to the question is r/t=7/3, choice (E).</p>

9

<p>4th one: The cubes that have NO paint on them are INSIDE (they are fully protected from the paint. 27 = 3<em>3</em>3, so there are 3 cubes in each direction. We need to extend this to 5 cubes in each direction (one on each side to fully protect the other 3 from the paint). So all together there are 5<em>5</em>5 = 125 cubes.</p>

10

<p>Be careful with the second problem. Plugging in the points gives p = 2 OR p=-2, and t = 4 OR t = -4. The slope is m = 12/(p-t). The safest thing to do now is try ALL 4 possibilities for p and t:</p>

<p>p=2, t=4 : m = 12/(2-4) = 12/(-2) = -6</p>

<p>p=2, t=-4 : m = 12/(2+4) = 12/6 = 2</p>

<p>p=-2, t=4 : m = 12/(-2-4) = 12/(-6) = -2</p>

<p>p=-2, t=-4 : m = 12/(-2+4) = 12/2 = 6</p>

<p>The least number that came out is -6, so -6 is the answer.</p>

<p>If you happened to only take the positive square roots here, you would have gotten lucky, but sometimes on a hard SAT question, the correct answer will involve taking the negative number, so BE CAREFUL!</p>

11

<p>Omg. Thanks guys! You’re all the best.</p>

12

<p>Here are some more I need explained:</p>

<p><a href=“http://i.imgur.com/qIxQm.png[/url]”>http://i.imgur.com/qIxQm.png&lt;/a&gt;
C</p>

<p><a href=“http://i.imgur.com/sYdXI.png[/url]”>http://i.imgur.com/sYdXI.png&lt;/a&gt;
9.8</p>

<p>Thanks!!</p>

13

<p>For the one that is 9.8, you can first get the side between the 5 and 7 is going to be 2. To get the other side, make a proportion. 2/5=x/7. X will equal 2.8. Add 2.8 and you have 9.8.</p>

<p>To get the answer of 100, first know the average rate which is (2<em>rate1</em>rate2)/(rate1+rate2). 2<em>50</em>25/(25+50)=33.33 average for one hour. Therefore, times that by 3 and you have 100.</p>