Question

Am I correct??

Answer 1

Use FOIL to write the four products
(2sqrt(3x)-2) (3 sqrt(3x)+5)
First: 2sqrt(3x)* 3 sqrt(3x)
Outer: 2sqrt(3x)*5
Inner: -2*3sqrt(3x)
Last: -2*5

can you simplify each of these products ?

Answer 2

what? im confused.. no i cant

Answer 3

@phi??????

Answer 4

ANYONE???

Answer 5

This explains it
http://www.khanacademy.org/math/algebra/polynomials/multiplying_polynomials/v/multiplying-binomials

Answer 6

but right now, try simplifying
\[ 2 \cdot \sqrt{3x} \cdot 3 \cdot \sqrt{3x} \]

Answer 7

when you multiply, you can change the order, so this is the same as
\[ 2 \cdot 3\cdot \sqrt{3x} \cdot \sqrt{3x} \]

Answer 8

2 times 3 is easy. It is 6

the square root of something times itself "gets rid of" the square root

Answer 9

I am only suppose to simplify not solve

Answer 10

we are doing your problem step by step. The first step is simplify
\[ 2 \cdot 3\cdot \sqrt{3x} \cdot \sqrt{3x} \]

Answer 11

oh ok

Answer 12

yes

Answer 13

ok so you were saying...

Answer 14

so is it 6 times 9

Answer 15

@phi

Answer 16

3*3 is 9

sqrt(3) * sqrt(3) is 3

remember: sqrt(this_is_anything) * sqrt(this_is_anything) = this_is_anything
try again.

and don't forget the x

Answer 17

yes, and 6*x*3 is the same as 6*3*x (change the order)
and 6*3 is 18, so you get
18x

next, simplify this one (we can't do a whole lot with it)
2*sqrt(3x)*5

Answer 18

(10) (sqrt3x)

Answer 19

is this right

Answer 20

yes. next
-2*3sqrt(3x)

Answer 21

is this (-6x) (3( sqrt3x))

Answer 22

you have an extra x. -2*3*sqrt(3x) is just -6 * sqrt(3x) or -6sqrt(3x)

Answer 23

now what??

Answer 24

how do i know what the answer is

Answer 25

The last one is -2*5, which is -10

let's write down what we got so far, added up
18x + 10sqrt(3x) + -6sqrt(3x) -10

we can simplify this by combining the sqrt(3x)'s we have 10 sqrt(3x) and take away 6 sqrt(3x)'s How many sqrt(3x)'s do we have left ?

Answer 26

4??

Answer 27

yes, but write it 4 sqrt(3x)

we simplify
18x + 10sqrt(3x) + -6sqrt(3x) -10

to be
18x +4 sqrt(3x) -10

that is the answer.

But watch the video to see how we get the 4 factors that we simplified. See if you can do the steps on your own.

Answer 28

oh ok i will thanks

Answer 29

do yuo get this one??

Answer 30

use ln(a) + ln(b) = ln(a*b)

in other words rewrite the sum of two logs as the log of a times b
can you do that?

Answer 31

no... Im lost

Answer 32

I have no idea how to do this...

Answer 33

OK, here is a lesson on how to interpret a formula

if we write ln(a)+ln(b) = ln(a*b)
that means look at your problem. If it is ln(some_number) + ln(another_number)
you can replace it with
ln(some_number times another_number)

example: ln(2)+ln(5) can be replace with ln(2*5) or ln(10)


now use the rule ln(a)+ln(b) = ln(a*b) on your problem
1n2+1nx=5

Answer 34

the rule also works for letters like x

Answer 35

but what do i do with the =5

Answer 36

one step at a time

Answer 37

@phi??

Answer 38

yes, but you replace ln2 + ln x with ln 2x in your equation
1n2+1nx=5

Answer 39

or what do you mean

Answer 40

@phi?

Answer 41

that is it.

you now have

ln(2x)= 5

now we want to get rid of the ln (natural log) which is the log base e
make each side the exponent of e
\[ e^{ln(2x)} = e^5 \]
the ugly stuff on the left becomes 2x (e raised to the ln(stuff) is stuff. e undoes the ln)

you get
2x = e^5
divide both sides by 2
x= e^5/2

Answer 42

you need a calculator

and they want the answer
round to nearest thousanth if nessasary

Answer 43

this right

Answer 44

\[ x= \frac{e^5}{2} \]

Answer 45

e is a number 2.718.... roughly 3 and 3*3*3*3*3 is way bigger than 12

Answer 46

remember, you do powers before dividing

yes. that is much better.

Answer 47

oh goood!

you had helped me half way on this ... Im confused
combine like terms . what is the simpler form of the expression
2(x/2-5)- 3/2(x+7/4)

Answer 48

multiply 2 times each thing inside the parens.
do the same with the -3/2
can you do that ?

Answer 49

@phi is it 2 x/2 -10 - 3/2x +21/8

Answer 50

yes
I would write -3/2 * x as -3x/2 it is clearer that 2 is in the denominator

but -3/2 * 7/4 is -21/8 not +

but mostly correct.
you have so far

2x/2 -10 -3x/2 - 21/8

you can add the x's (they have a common denominator of 2)
you can add -10 + -21/8
but first you need to multiply -10 by 8/8

Answer 51

isnt it -10

Answer 52

8/8 is 1 times -10

Answer 53

yes, but we want -80/8 so you have a common denominator with -21/8

Answer 54

ok

Answer 55

what does that mean

Answer 56

to add fractions

or you could change -21/8 into a decimal number.

Answer 57

-2.625

Answer 58

so i would add -2.625 and what??

Answer 59

2x/2 -10 -3x/2 - 21/8

numbers to numbers so -10 - 2.625
and x's with x's
(2x-3x)/2 or -x/2

-x/2 -12.625 is one way to write it
or
-x/2 - 101/8 is another way

Answer 60

is that the answer

Answer 61

Is this the answer

Answer 62

@Phi?? I promise this is the last question

Answer 63

yes. See my post up above

Answer 64

oh ok thanks sooooo much!!