Question

SIMPLIFY??
3√45 - 8√20

Answer 1

@jim_thompson5910 helpp?(:

Answer 2

-15.6524758425

Answer 3

how would you simplify \(\Large \sqrt{45}\)

Answer 4

@jim_thompson5910 you can't right? but the square root of 45 is 6.70

Answer 5

can you factor 45 into two numbers where one of them is a perfect square?

Answer 6

@jim_thompson5910 yes 9 and 5, 9 would be the perfect square

Answer 7

good

Answer 8

so

\[\Large \sqrt{45} = \sqrt{9*5}\]

Answer 9

@jim_thompson5910 okay..

Answer 10

then you use the rule \[\Large \sqrt{x*y} = \sqrt{x}*\sqrt{y}\]

Answer 11

\[\Large \sqrt{45} = \sqrt{9*5}\]
\[\Large \sqrt{45} = \sqrt{9}*\sqrt{5}\]
\[\Large \sqrt{45} = ???\]

Answer 12

@jim_thompson5910 i don't know :(

Answer 13

3√45 - 8√20

= 3√9*5 - 8√4*5

= 9√5 - 16√5

= -7√5

I go this from Yahoo Answers, does it help? It helped me. :)

Answer 14

Do you see how I got

\[\Large \sqrt{45} = \sqrt{9*5}\]
\[\Large \sqrt{45} = \sqrt{9}*\sqrt{5}\]

Answer 15

@jim_thompson5910 yes I see you used the equation from above..

Answer 16

what is the square root of 9

Answer 17

@CrazyCountryGirl thanks but I need a little more in depth help. :)

Answer 18

@jim_thompson5910 3 is the square root of 9

Answer 19

so,

\[\Large \sqrt{45} = \sqrt{9*5}\]
\[\Large \sqrt{45} = \sqrt{9}*\sqrt{5}\]
\[\Large \sqrt{45} = 3*\sqrt{5}\]

Answer 20

OK. :) Sorry I couldn't help more.

Answer 21

@jim_thompson5910 oh okay i see..

Answer 22

so how would you simplify \[\Large \sqrt{20}\]

Answer 23

it would be 5 and 4 where 4 is the perfect square. and it would be √20= √5*4

Answer 24

so far so good

Answer 25

√20 = √5 √4

Answer 26

keep going

Answer 27

@jim_thompson5910 so it would be √20 = 2*√5

Answer 28

good

Answer 29

summing up we have so far

\[\Large \sqrt{45} = 3*\sqrt{5}\]
\[\Large \sqrt{20} = 2*\sqrt{5}\]

Answer 30

those two facts allow us to go from

\[\Large 3*\sqrt{45} - 8*\sqrt{20}\]

to

\[\Large 3*3*\sqrt{5} - 8*2*\sqrt{5}\]

Answer 31

@jim_thompson5910 so it would be 9 * √ 5 - 16 * √ 5

Answer 32

good, what's next?

Answer 33

then you subtract 9-16 and it would be -7√5

Answer 34

@jim_thompson5910 thank you so much. :) saved my life.. haha

Answer 35

you're welcome