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sahimwallace

11 years agoPosted 11 years ago. Direct link to sahimwallace's post “At 0:28, you added all th...”

At

0:28

, you added all the values and observed that if the sum was divisible by 3, so was the value. What video can I find this principle?•

(193 votes)

Sam

10 years agoPosted 10 years ago. Direct link to Sam's post “The link is broken, here ...”

The link is broken, here is the new one:

https://www.khanacademy.org/math/pre-algebra/factors-multiples/divisibility_tests/v/divisibility-tests-for-2-3-4-5-6-9-10(128 votes)

Nathan Shapiro

10 years agoPosted 10 years ago. Direct link to Nathan Shapiro's post “At 0:09, Sal said that 11...”

At

0:09

, Sal said that 117 is not a perfect square. What does that mean?•

(42 votes)

я̿€̿ρ̿Ł̿ɪ̿т̿Ǻ̿ƶ̿

10 years agoPosted 10 years ago. Direct link to я̿€̿ρ̿Ł̿ɪ̿т̿Ǻ̿ƶ̿'s post “A perfect square is a squ...”

A perfect square is a square root is not a decimal. You can not take the square root of 117 and have it not be a decimal. But if you were to take the square root of 9, it would be 3 because 3x3=9. Hope this helped!

(63 votes)

Matt Stringer

6 years agoPosted 6 years ago. Direct link to Matt Stringer's post “I'm having a LOT of troub...”

I'm having a LOT of trouble siplifying square roots and I can't understand why it's not making any sense to me...

The Square Roots Practice I can finish in about 10 seconds but I'm really hitting a wall with the Simplification side of Square Roots. Please help me!•

(60 votes)

learn

6 years agoPosted 6 years ago. Direct link to learn's post “I will try to give you a ...”

I will try to give you a couple of examples to help you. If you have a perfect square like √4 you know 2*2 = 4 so √4=2

but what if you had √12? It isn't a perfect square but it can still be simplified by finding any perfect squares within it and removing them. To see if we have any perfect squares we can do a prime factorization of 12. 12 = 2*2*3 Since we have a perfect square within the 12 we can say √12 = √4*3

so √12 = 2√3 (The 3 is prime and can't be reduced and the 2 used to be under the radical as √4).

Let's take √6 now. Prime factorization is √2*3 (We can't remove a perfect square so √6 is already in simplest form.

Let's take √24 now. Prime factorization is √2*2*2*3 (We have two 2's so we have a perfect square.) We can simplify this to √4*6 or 2√6

So to simplify a square root use prime factorization to find any perfect squares that you can remove from the total under the radical.(48 votes)

я̿€̿ρ̿Ł̿ɪ̿т̿Ǻ̿ƶ̿

10 years agoPosted 10 years ago. Direct link to я̿€̿ρ̿Ł̿ɪ̿т̿Ǻ̿ƶ̿'s post “Wouldn't the answer to a ...”

Wouldn't the answer to a square root really be positive and negative? For instance, if we wanted the square root of 9, it would be 3 and -3? because 3x3=9 and -3x-3=9?

•

(34 votes)

Rohini

10 years agoPosted 10 years ago. Direct link to Rohini's post “Yes, whenever you take sq...”

Yes, whenever you take square roots, you get two values (one positive and the other negative). But when you take the "principle" square root , you take only the positive value.

(46 votes)

andrea baek

10 years agoPosted 10 years ago. Direct link to andrea baek's post “Around 2:24, Sal explains...”

Around

2:24

, Sal explains that 5*3 and the square root of thirteen is 15 times the square root of thirteen. Why would you multiply the numbers 5 and 3?•

(30 votes)

Nathan Shapiro

10 years agoPosted 10 years ago. Direct link to Nathan Shapiro's post “He is trying to simplify ...”

He is trying to simplify it. 5•3•√13 is more complex than 15•√13. The former has 3 steps involved (multiply 5 and 3, find square root of 13, multiply 15 by square root of 13), while the latter only has 2 steps involved (find square root of 13 and multiply by 15).

(36 votes)

Chris

9 years agoPosted 9 years ago. Direct link to Chris's post “Which video (and where) e...”

Which video (and where) explains why you can add up the digits of a number to see if it's divisible by 3 like at

0:25

-0:36

?•

(22 votes)

sean

9 years agoPosted 9 years ago. Direct link to sean's post “go to pre- algabra and in...”

go to pre- algabra and in the factors and multiples section you will find divisablity tests at the top of the list and it explains the rule for 3 in the first video

(31 votes)

AliAfrose

8 years agoPosted 8 years ago. Direct link to AliAfrose's post “what is the concept of si...”

what is the concept of simplifying square roots? I don't understand square roots

•

(17 votes)

Johnathan

8 years agoPosted 8 years ago. Direct link to Johnathan's post “Roots are the inverse ope...”

Roots are the inverse operation to powers. So if you take the square root of 6 and then you square it, then you would be left with 6 because the square and the square root cancel out.

Now if you have the square root of 2 plus the square root of 2, you would have 2√2. Notice that it isn't √4. It is actually 2√2 (which is the same as √8).

So the concept of simplifying square roots is like the concept of simplifying other things like exponents, parentheses, etc.

(4 votes)

Palaash Dwivedi

8 years agoPosted 8 years ago. Direct link to Palaash Dwivedi's post “i still don't understand ...”

i still don't understand the concept

•

(13 votes)

Jhonella Maceren

8 years agoPosted 8 years ago. Direct link to Jhonella Maceren's post “I found a website that br...”

I found a website that breaks this concept down as if they were teaching it to kindergarten students XD

https://www.mathsisfun.com/numbers/simplify-square-roots.htmlHelped me finally understand this!

(21 votes)

Vivian

9 months agoPosted 9 months ago. Direct link to Vivian's post “sometimes i look at the c...”

sometimes i look at the comments because they're funny.

•

(20 votes)

Lady Ann

7 months agoPosted 7 months ago. Direct link to Lady Ann's post “Yup, I also look at the c...”

Yup, I also look at the comments to give some upvotes. (And maybe a few badges as well)

(6 votes)

Duncan Whitmore

9 years agoPosted 9 years ago. Direct link to Duncan Whitmore's post “Okay so how would you do ...”

Okay so how would you do fractions? I'm very confused and my math teacher sped through it so I didn't understand. How would you simplify the sqare root of 35 over 9 (just and example)?

•

(12 votes)

Jay

9 years agoPosted 9 years ago. Direct link to Jay's post “The thing about a square ...”

The thing about a square root of a fraction is that:

sqrt(35/9) = sqrt(35)/sqrt(9)

in other words, the square root of the entire fraction is the same as the square root of the numerator divided by the square root of the denominator. With that in mind, we can simplify the fraction:

sqrt(35)/3

As you can see, I left the numerator under the square root, because I can't simplify it, but the square root of 9 is three so I could replace the sqrt(9) in the denominator by 3.

The same rule applies to exponents: e.g. (2/3)^2=(2^2)/(3^2)(12 votes)