Smart people-- Help with explanations!

Test Preparation SAT Preparation
1

<p>I bought the big blue book and I was reviewing for the math portion of it. The first half of the review have explanations, but the second half doesn’t. I need to know how these people got their answers! Dx
Please help! And don’t brag that you’re smarter or be like, “OMG, you don’t know how to do that!? I learned that in 2nd grade! ” </p>

<p>Pg. 361 # 8</p>

<p>((Square root of) x^2-t^2 = 2t-x </p>

<p>"If x and t are positive numbers that satisfy the equation above, what is the value of x/t?"</p>

<p>I got something like x/(2/3)x ...</p>

<p>Answer: 5/4</p>

<hr>

<p>Pg. 368 # 5.</p>

<p>Which of the following is an equation of the line that has a y-intercept of 2 and an x-intercept of 3?
A. -2x + 3y = 4
B. -2x + 3y = 6
C. 2x + 3y = 4
D. 2x + 3y = 6
E. 3x + 2y = 6</p>

<p>Answer: D</p>

<p>Could you tell me how you got the answer and easy ways to rule out choices unlikely.</p>

<hr>

<p>369 # 8
There’s a graph that goes with it, but I can’t draw it on here or anything.
It starts from 0 and shows up to 5. It touches 0 at 1.3, 2.3, 3, and 4.5 (estimates)</p>

<p>The figure above shows a portion of the graph of the function f. If f(x+5)=f(x) for all values of x, then f(x) = 0 for how many different values of x between 0 and 12?</p>

<p>A. 8 B. 9 C. 10 D. 11 E. 12</p>

<p>I chose A.</p>

<p>Answer: B. 9</p>

<hr>

<p>Pg. 373 # 4. Writing part</p>

<p>If ¼ of 4/3 is subtracted from 2, what is the resulting value?</p>

<p>I got -5/3.</p>

<p>Answer: 5/3</p>

<p>Why isn’t is negative? Is it positive because there isn’t a minus sign in the answer booklet?</p>

<hr>

<p>That's about it for now, and thanks :)</p>

<p>~!~!Have a good day~!~! ^o^</p>

2

<h2>First question: square both sides of the equation and play with it. I bet you can cancel certain terms and you can get x/t.</h2>

<p>Which of the following is an equation of the line that has a y-intercept of 2 and an x-intercept of 3?
A. -2x + 3y = 4
B. -2x + 3y = 6
C. 2x + 3y = 4
D. 2x + 3y = 6
E. 3x + 2y = 6</p>

<p>Answer: D</p>

<p>To find the y-intercept, plug in 0 for the x value. For the x-intercept, plug in 0 for the y value.</p>

<hr>

<p>Pg. 373 # 4. Writing part</p>

<p>If ¼ of 4/3 is subtracted from 2, what is the resulting value?</p>

<p>I got -5/3.</p>

<p>Answer: 5/3</p>

<p>Why isn’t is negative? Is it positive because there isn’t a minus sign in the answer booklet?</p>

<p>* Do this step by step. First, what is 1/4 of 4/3? That’s 1/4 x 4/3, right? and that’s 1/3. Now, next step. This value (1/3) is subtracted FROM 2. Which means you do 2 - 1/3 = 5/3.*</p>

<hr>

<p>Sorry for the rushed answers and I didn’t do all of them. Lazy + busy :/</p>

3

<p>First square both sides.</p>

<p>x^2 - t^2 = (2t-x)^2
x^2 - t^2 = 4t^2 - 4tx + x^2
-5t^s = -4tx
-5t = -4x
(5/4)t = x
x/t = 5/4</p>

<p>Wow that was so easily, I learned that in like second grade… Just kidding :)</p>

4

<p>alright here’s #1. what frustrates me is i could always do this at home and get 800’s, but when i get to the test, my mind wanders and i ***** it all up. anyway:</p>

<p>first, square both sides to get:
x^2 - t^2 = 4t^2 - 4tx + x^2</p>

<p>cancel out x^2 on either side to get </p>

<p>-t^2 = 4t^2 - 4tx</p>

<p>then, bring tha t^2 together to get</p>

<p>-5t^2 = -4tx</p>

<p>then cancel out the minuses. cancel out a t from each side to get</p>

<p>5t = 4x</p>

<p>then divide 4x by 5t to get</p>

<p>(4/5) (x/t) = 1</p>

<p>then multiply left and right sides by 5/4 to yield (drumroll)…</p>

<p>x/t = 5/4.</p>

5

<p>Uh, for the y and x intercept stuff, I don’t really get what you’re trying to say.
(0,2) for the y intercept & (3,0) for the x intercept… I get that, but how do you find the answer?
I understand the second one, thanks, just need to read between the lines on that stuff I suppose.</p>

6

<p>Which of the following is an equation of the line that has a y-intercept of 2 and an x-intercept of 3?
A. -2x + 3y = 4
B. -2x + 3y = 6
C. 2x + 3y = 4
D. 2x + 3y = 6
E. 3x + 2y = 6</p>

<p>Point-slope form –> y-y1 = m(x - x1)
the 2 points are (0,2) and (3,0)
slope = (0-2)/(3-0) = -2/3
y - 0 = (-2/3)(x - 3)
y = (-2/3x) = 2
y + (2/3)x = 2
3y + 2x = 6 ------> D
That was so easy I learned that in like 1st grade… :)</p>

7

<p>And Strange already answered your third question.</p>

8

<p>Oh, okay, thanks :slight_smile: I get it now, but I don’t know if I could repeat it on a test; I’m going to review it one more time.</p>

<p>And for the square root one, I forgot to foil & I thought the square root and squaring cancelled out so I didn’t do anything to the right side.</p>

<p>Thanks so much xP</p>