Question

Math help

Answer 1

Part two of a pre test please help i have answers just need corrections
@iambatman @nincompoop @wolfe8 @whpalmer4

Answer 2

@whpalmer4 will you be helping me?

Answer 3

I think 2 is wrong

Answer 4

I also think 2 is incorrect. Same with 4 and 5

Answer 5

can you correct me ?

Answer 6

on the ones that are wrong?

Answer 7

Why don't you show us how you did the problems? Often more productive to see where you went wrong...

Answer 8

For 2, ur actually solving for

3=x-5
----
3

Answer 9

for #5, a quick check: does the point (2,2) work in your chosen answer?

Answer 10

Becuz it's inverse, u switch the x and y

Answer 11

thanks i threw away all the work. Thanks for trying anyways :)

Answer 12

that's no excuse for trying the point in the equation as I suggested...

Answer 13

you chose \[(y-8) = -3(x-4)\]as an equation for the line passing through (2,2) and (4,8).

Does that equation actually work with x=2, y=2? How about x=4, y=8? It has to satisfy both of them to be correct.

Answer 14

2-8 = -3(2-4)
-6=-3(-2)
-6=6
Oops!

Answer 15

I have to go anyways im at the library and my time limit is running out lol if u can check my answers and correct them before 9:40 I would appreciate it but thanks anywyas :)

Answer 16

Well, that's one way you can find a valid answer — rule out the wrong ones!

For #4, the average rate of change problem: x goes from -1 to 4, so it increases by 5. at the same time, y goes from 5 to 0, so it decreases by 5. -5 / 5 = -1, no? increase or decrease / change in x gives you average rate of change

Answer 17

For 5, the slope is 3, so u can rule out Cd and D already.
Now all u gotta do is plug (2,2) into the point slope equation

y-y1 = m(x-x1)

Answer 18

So 1 is correct r incorretc?

Answer 19

for problem #4, the correct answer is -1. for problem #5, the 1st answer is correct.

another way of thinking of average rate of change is that it is just the slope of the line between the two points.

Answer 20

And yes, 1 is correct

Answer 21

for 2 and 3 im a bit confused on those

Answer 22

I told u 2 and for 3, use the slope formula

Answer 23

okay let me see if i can figure it out but the ones i posted are incorrect rigth?

Answer 24

y2-y1
--------
x2-x1

Answer 25

So
4-0
------
0-(-2). Would be ur slope

Answer 26

4/2 or 2 which is c thats for 3 im a bit confused on 2

Answer 27

So for example,

f(5)= x+2
5 would be what u plug in for x so u get the expression 5+2

Does this make sense so far?

Answer 28

yea

Answer 29

And that means f(5)=7

Answer 30

And in ur problem it's

f(x)=x-5
-----
3

Answer 31

yea

Answer 32

Or u can say

y=(x-5)/3

But because ur looking for f^-1 (x)
U switch the x and y

Answer 33

So x=(y+5)/3

Plug in 3 for x

And get

3=(y+5)/3

And solve for y

Answer 34

okay im gonna go with c 18

Answer 35

No, it's suppose to be B14 and I made a typo

Answer 36

ohh k for 6 is it a?

Answer 37

3=(y-5)/3
Multiply both sides by 3
9=y-5
And finally add 5 to both sides

Answer 38

Yea, 6 is correct

Answer 39

okay i have 4 more can u go over em ?

Answer 40

7 is wrong

Answer 41

,its suppose to b a

Answer 42

unfortunately all are wrong :-(

Answer 43

ohh :(

Answer 44

please can you correct the 4 real quick I have to leave the library at 10:10

Answer 45

\[2\sqrt[4]{80} = 2\sqrt[4]{2*2*2*2*5} = 2*2\sqrt[4]{5}\]with a 4th root, you take one copy of each 4 identical factors out

Answer 46

ohh okay i see so its a

Answer 47

\[\sqrt{75}-4\sqrt{8}-3\sqrt{32} = \sqrt{3*5*5}-4\sqrt{2*2*2}-3\sqrt{2*2*2*2*2}\]\[=5\sqrt{3}-2*4\sqrt{2}-3*2*2\sqrt{2}\]you can see the rest

Answer 48

is it c?

Answer 49

complex conjugates:
\[(a+bi),(a-bi)\]You just change the sign of the complex part. \(4+3i\) would be the right answer

Answer 50

\[5\sqrt{3}-2*4\sqrt{2}-3*2*2\sqrt{2} = 5\sqrt{3}-8\sqrt{2}-12\sqrt{2} = 5\sqrt{3}-20\sqrt{2}\]

Answer 51

okay 10? Is kinda complicated can u show me step by step?

Answer 52

\[\frac{\sqrt{-16}}{(3-3i)+(1-2i)}\]let's do the top first:

\[\sqrt{-16} = \sqrt{-1*16} = \sqrt{-1}*\sqrt{16} = i*4 = 4i\]Agreed?

Answer 53

For the denominator:

\[(3-3i)+(1-2i) = 3-3i+1-2i\]collect like terms\[3+1-3i-2i=4-5i\]

Answer 54

yes its b corretc?

Answer 55

so now we have \[\frac{4i}{4-5i}\]To rationalize that (get rid of the complex part of the denominator) we multiply both numerator and denominator by the conjugate of the denominator. This is like multiplying by 1, so it doesn't change the value, but it allows us to clear out the complex number in the denominator:

\[\frac{4i}{(4-5i)}*\frac{(4+5i)}{(4+5i)} = \frac{4*4i + 4i*5i}{4-20i+20i-25i^2} = \frac{16i+20i^2}{4-25i^2}\]

Answer 56

but remember that \[i = \sqrt{-1} \rightarrow i^2 = (\sqrt{-1})^2 = -1\]so that means our fraction goes from \[\frac{16i+20i^2}{16-25i^2} =\frac{16i+20(-1)}{16-25(-1)} = \frac{16i-20}{41}\]

(sorry, I wrote \(4-25i^2\) in the denominator in the previous post, but it should have been \(16-25i^2\))

Answer 57

so its d?

Answer 58

yes. the answer has the terms in a different order, but the value is the same.

Answer 59

ohh okay i understadn tahnks alot :)

Answer 60

this rationalization technique gets used with complex numbers, square roots, trigonometry, you'll see it often!