Question

I need someone to work me through this please!Nakim simplified 3 times the square root of 2x plus x times the square root of 8x minus 5 times the square root of 18x and got -10x times the square root of 2x for an answer.

Part 1: Using complete sentences, explain what Nakim did wrong.

Part 2: Show all your work to simplify the expression.

Answer 1

You'll have to try to learn to use the equation editor... don't make people decipher things like this

"3 times the square root of 2x plus x times the square root of 8x minus 5 times the square root of 18x"

\[\Large 3\sqrt{2x} + x \sqrt {8x} - 5\sqrt{18x}\]

Answer 2

I'm sorry, I wasn't thinking

Answer 3

yes that's the equation and he got \[-10\sqrt{2x}\]

Answer 4

start simplifying it by looking for perfect squares\[\Large 3\sqrt{2x} + x \sqrt {4*2x} - 5\sqrt{9*2x}=\] \[\Large 3\sqrt{2x} + x \sqrt {4}*\sqrt{2x} - 5\sqrt{9}*\sqrt{2x}=\]

Answer 5

what does * mean?

Answer 6

I don't understand

Answer 7

* means multiply. All I've done is simplify it a bit, by breaking up some square roots. What part don't you understand?

Answer 8

\[\Large 3\sqrt{2x} + x \sqrt {8x} - 5\sqrt{18x} = \] \[\Large 3\sqrt{2x} + x \sqrt {4*2x} - 5\sqrt{9*2x}= \] \[\Large 3\sqrt{2x} + x \sqrt {4}*\sqrt{2x} - 5\sqrt{9}*\sqrt{2x}=\]

Answer 9

do I multiply the inside with the outside? or do I find the square root of the inside and multiply that by the outside?

Answer 10

3x+2x*sqrt 2x- 15* sqrt 2x?

Answer 11

Just simplify any pieces you can...like the sqrt of 4. And the sqrt of 9.

Answer 12

\[\Large 3\sqrt{2x} +2x \sqrt{2x} - 15\sqrt{2x}=\]

Answer 13

then what do I do?

Answer 14

Now combine like terms. What would 3x+2x-15x be equal to?

Answer 15

Sorry, i corrected it. They all have the same srt2x, so treat it the same way.

Answer 16

-11x sqrt 2x

Answer 17

did I just solve it :D

Answer 18

no its -9x!

Answer 19

Almost. Maybe try factoring out the common factor sqrt 2x \[\Large 3\sqrt{2x} +2x \sqrt{2x} - 15\sqrt{2x}= \] \[\Large \sqrt{ 2x} (3 +2x - 15)= \]

Answer 20

do I add 12 to 2x?

Answer 21

-12*

Answer 22

Which 12? you can change the order like so \[\Large \sqrt{ 2x} (3 -15 +2x)=\]

Answer 23

No, you can't combine 2x and -12, they are not like terms.

Answer 24

so -12+2x sqrt 2x

Answer 25

\[\Large \sqrt{ 2x} (-12 +2x)=\] Now distribute the sqrt2x back into the brackets

Answer 26

Now you can see the guy's mistake... he combined -12 and 2x into -10x

Answer 27

thank you! so the solution is?

Answer 28

Just distribute that sqrt2x back into the brackets

Answer 29

hmm -12+2xsqrt2x?

Answer 30

You didn't distribute it correctly, it has to distribute to BOTH terms.

Answer 31

im confused :(

Answer 32

A(B + C) = AB + AC
Try using that on \[\Large \sqrt{ 2x} (-12 +2x)=\]

Answer 33

-12x+2x
10x

Answer 34

Wait... no. Make sure you don't change anything like that.

\[\Large \sqrt{ 2x} (-12 +2x)= -12 \sqrt{2x} + 2x \sqrt {2x}\]

Answer 35

ohh ok sorry

Answer 36

so that's the answer

Answer 37

Yes. Just be careful using the distributive property.

Answer 38

You can also do it this way (might've been easier). Change the order:
\[\Large 3\sqrt{2x} +2x \sqrt{2x} - 15\sqrt{2x}= \] \[ \Large 3\sqrt{2x} - 15\sqrt{2x} +2x \sqrt{2x} =\]

Answer 39

alright thank you!!

Answer 40

Welcome :)