Math questions

Test Preparation SAT Preparation
1

<p>"In the xy-coordinate plane, lines l and q are perpendicular. If line l contains poitns (0,0) and (2,1), and line q contains the points (2,1) and (o, t), what is the value of t?"</p>

<p>I got -3 thinking the slope of the first line is 1/2x (l) and then q would be -2x so I got t as -3, it's the slope is -2, it'd be (0, -3) (1, -1) and (2,1). Where did I go wrong in this picture?</p>

<p>And the second question isn't really a question, I mean it is a qusetion on page 456 # 17 of BB2 but i just want to understand the concept. They give you a picture and the equation of a regular line: y=-2x+6 and ask what would the graph look like if it were changed to y=|-2x+6|. What happens when a line is absolute valued? I forgot this it's been so long, kind of a shame cuz i'm in ap calc BC too >.></p>

<p>Like do all the negative y values just turn positive and it replicates the mirror y values similiar to a parabola except it's more exact values and not curved liek a parabola?</p>

2

<p>page 468 # 17: The cost of a telephone call using long-distance carrier A is $1.00 for any time up to and including 20 minutes and $.07 minute thereafter. The cost of using long-distance carrier B is $.06 per minute for any amount of time. For a call taht lasts t minutes, the cost using carrier A is the same as th cost using carrier B. If t is a positive integer greater than 20, what is the value of t?</p>

<p>another one of those comparing rates question.</p>

<p>465 # 8 Meredith has a red hat, blue hat and a white and one red, blue, white sweater and 3 pairs of jeans: red, blue and white. Meredith wants to wear a red, white and blue outfit consisting of one hat, one sweater and one pair of jeans. how many different possibilities does she have?</p>

<p>I just did 3x2x1 based on how many possibilities there were per slot but is ther eanother way to do it?</p>

3

<ol>
<li>Since t is over 20, we know that carrier A’s $1.00 charge will be used up. The comparison can be represented as follows:</li>
</ol>

<p>.07(t - 20) + 1 = .06(t)
.07t - 1.4 + 1 = .06t
.01t = .4
t = 40 minutes</p>

<ol>
<li>If the hat is red, the sweater and jeans must be white and blue (two combinations). If the hat is blue, the sweater and jeans must be white and red (two combinations). If the hat is white, the sweater and jeans must be blue and red (two combinations). 2 + 2 + 2 = 6.</li>
</ol>

4

<p>anyone else? >.></p>

5

<p>page 485 of BB2 #13
If n is a positive integer and 2^n+2^n+1=k what is 2^n+2 in term of k?
a) (k-1)/2
b) 4k/3
c) 2k
d) 2k+1
e) k^2</p>

6

<p>^ You need to rewrite that one. Does it read 2^n + 2^(n+1), or is the 1 outside the exponent?</p>

7

<p>oh right sorry it’s
2^n+2^(n+1)=k
What is 2^(n+2)?</p>

<p>And yes i know i could just substitute a value for and get that it’s 4k/3 but what’s the algebraic way even though substituting seems to be faster in this case lol</p>

8

<p>2 ^ (n) + 2 ^ (n+1) = k
2 ^ n * (1 + 2) = k
3 * 2 ^ (n) = k</p>

<p>2 ^ (n + 2)
= 2 ^ (n) * 2 ^ (2)
= (k / 3) * 4
= 4k / 3
= B</p>

<p><em>pounds head against desk</em>
I am an idiot for taking so long to see this :(</p>

9

<p>that’s dirty lol wow… thanks… yea substituting was definitely quicker than all that lmao thank goodness it was a multiple choice</p>

10

<p>The actual solution was quite simple… it just took me forever to spot it. At least that was more fun than most SAT questions :)</p>