Question

http://prntscr.com/ddf59u

Answer 1

@harman.singh

Answer 2

Notice that
\[\sqrt{20}=\sqrt{5} \times \sqrt{4}\]

Answer 3

Haan :)

Answer 4

\[\sqrt{5} \times \sqrt{4} = \sqrt{5} \times 2\]

Answer 5

I was gonna help too ):

Answer 6

So the first equation 4 sqroot of 20 can be written as
\[4 \times 2 \times \sqrt{5}\]

Answer 7

its equals - /5

Answer 8

Acha (y)

Answer 9

Do you know how to do the rest now?

Answer 10

Um not really... :/

Answer 11

alright so i can help you but what if pooja came in and remove my answers again LMAO

Answer 12

She's nice. :p

Answer 13

convert that expression into rational expression to get
\[20^(1/4) - 45^(1/3) = 1.44\]
which is equivalent to D

Answer 14

and yeah sure she is lol

Answer 15

So this is how you would simplify 4/20
\[4\sqrt{20}\]
- write the squareroot value as multiplication of two different squareroots
\[=4 \times \sqrt{5} \times \sqrt{4}\]
- We know that sqroot of 4 is simply 2. So we can simplify it further in the next step
\[4 \times \sqrt{5} \times 2\]
- We now multiply the two like terms together..
\[8\sqrt{5}\]

Answer 16

OKay, I got that

Answer 17

Badia. Now its the same procedure for the other term in the question.
\[4\sqrt{20}-3\sqrt{45}\]
\[8\sqrt{5}- ???\]
Can you try and simpify 3/45? I will help you if you get stuck anywhere

Answer 18

Okay but 45 doesn't have a perfect square... :/ How will you do that?

Answer 19

Think about the numbers that multiply together to give you 45. Can you list them for me please?

Answer 20

9 x 5

Answer 21

9 has a perfect square of 3

Answer 22

Haan sahi :)

So we can write /45 as:
\[\sqrt{5} \times \sqrt{9}\]

Answer 23

So -/5 x -/9 x 3?

Answer 24

Is that a negative sign in front of /5 & /9? Not sure what that really means

Answer 25

no lol
sqroot

Answer 26

Oh achla lol. But its correct so far :)

Answer 27

-/105

Answer 28

Umm...I am not sure where you are getting 105 from.

So we had..
\[\sqrt{5} \times \sqrt{9} \times 3\]
As you said above, 9 is a perfect square of 3. So we can write -/9 as 3.
\[\sqrt{5} \times 3 \times 3\]

Answer 29

okay so then the answer is either 45 or 135 :/

Answer 30

I am not sure how you are getting 135?

Can you refer to my working out for the previous expression and see what I did there at the same step for this expression?

Answer 31

yeah
i did 5 x 3 x 3 and got 45

Answer 32

Dont forget that its -/5 , not just 5

Answer 33

So how would you do that then? :/

Answer 34

You should leave the sqroot of 5 written as it is in the answer.

\[\sqrt{5} \times 3 \times 3\]
\[=9\sqrt{5}\]

Answer 35

and thats the simplified version of 3-/45



The original question was..
\[4\sqrt{20}- 3\sqrt{45}\]
and we found simplified versions of both the equations above. Now, can you write those simplified answers togeher so that we can substract them from each other?

Answer 36

So we just subtract 3 from 4 and 45 from 20

Answer 37

No, thats the question. We have to write it in simplified form before subtracting.


We found that ..

4-/20 = 8-/5

& 3-/45 = 9-/5

So, \[4\sqrt{20}-3\sqrt{45}\]
= \[8\sqrt{5}-9\sqrt{5}\]

Answer 38

Now, we can subtract the two terms from each other to simplify our answer further

Answer 39

-7?

Answer 40

When subtracting, leave the sqroot of 5 as it is. You can think of sq5 as 'x'

So..

8x - 9x = ?

Answer 41

-1

Answer 42

haan.

-1x to be more precise.

Answer 43

Now replace sq5 with 'x' in your final answer.