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Mathematics 20 Online
OpenStudy (anonymous):

o

OpenStudy (anonymous):

Is 64 a perfect square?

OpenStudy (anonymous):

Is x^2 a square?

OpenStudy (aaronandyson):

is it \[x^2 + 64?\]

OpenStudy (anonymous):

What is the definition of a perfect square?

OpenStudy (anonymous):

Hmm I say we teach her If she gets it, medal is yours I'm not here for the medal i'm here to get her to understand the question :)

OpenStudy (aaronandyson):

takes the square 8 time 8 is 64

OpenStudy (anonymous):

How do you get x^2 in the first place? What two variables do you multiply to get it?

OpenStudy (anonymous):

Good! And what two numbers do you multiply to get 64? Obviously 8 right thanks to AA What do these two have in common x^2, 8^2

OpenStudy (anonymous):

Good! Taking the square out. You get (x+8)^2 Expanding this: (x+8)^2..... Will that give you x^2 + 64?

OpenStudy (anonymous):

Actually it would not (x+8)^2 gives you x^2 + 16x + 64 What does that tell you about factoring x^2 + 64?

OpenStudy (anonymous):

It tells you it cannot be factored It is simply impossible Every time you have something like x^2 + P where P is perfect square You cannot factor it. Does that make sense?

OpenStudy (aaronandyson):

There are no factors with real numbers. If you want complex number answer then (x + 8i)(x - 8i)

OpenStudy (anonymous):

^That is exactly what the answer should be if you're doing a test

OpenStudy (aaronandyson):

x^2 +64 = 0 And we get P(x)=x^2 +64 Now, we can look for the roots of P(x) using various Algorithm : Solve by Factorization x^2 +64 = 0 Separate : ( x^2 -8*i*x ) + ( 8*i*x +64 ) = 0 Commutative Law : ( x^2 8*i*x ) + ( -8*i*x +64 ) = 0 Distributive Law : x*( x 8*i ) + -8*i*( x 8*i ) = 0 Factor : ( x -8*i )*( x 8*i ) So the Polynomial have 2 roots : x1 = 8*i x2 = -8*i

OpenStudy (anonymous):

You're right There is no answer for that

OpenStudy (anonymous):

How about x^2 - 64 Do you think this is factorable?

OpenStudy (anonymous):

Look again. What changed from x^2 + 64 and x^2 - 64?

OpenStudy (anonymous):

Yep. And so that means there is a possibility that this is factorable. Going back to where we left off with the other one... we had (x+8). Putting a square outside would not make x^2 - 64

OpenStudy (anonymous):

What two combinations make a negative? Think + and - and multiplication

OpenStudy (anonymous):

Actually it doesn't matter which has the higher value in multiplication But you're right So to get x^2 - 64 What would you have to multiply (x+8) with?

OpenStudy (anonymous):

do you have to multiply it by (x+8) again or (x-8)?

OpenStudy (anonymous):

to check your answer Expand (x+8)(x-8) that should give you x^2 - 64

OpenStudy (anonymous):

Notice how when you're combining like terms, there seems to be some cancelling out during expansion

OpenStudy (anonymous):

The negative stuff was just a lesson you might learn later on For now, you want to stick with showing that you cannot factor the two expressions Show your work like AA showed his

OpenStudy (anonymous):

Do you know the value of i?

OpenStudy (anonymous):

nope i actually is \[i = \sqrt{x^{-1}}\]

OpenStudy (anonymous):

Can you square root that?

OpenStudy (aaronandyson):

use the FOIL method to remember how to multiply two binomials (a+b)(c+d) First: a*c Outer a*d Inner: b*c Last: b*d now add up to get ac+ad+bc+bd if you have (a+b)(c -d) treat it like (a+b)(c+ -d) and do the same thing First: a*c Outer: a*-d Inner: b*c Last: b* -d put it all together: ac -ad +bc -bd

OpenStudy (anonymous):

OOOPS so \[\ i = sqrt{-1}\]

OpenStudy (anonymous):

\[i = \sqrt{-1}\]

OpenStudy (aaronandyson):

just apply the (a+b)^2 formula (a+b)^2=a^2+b^2+2ab then you will get it....

OpenStudy (aaronandyson):

after appling the formula you will see i^2 replace i^2 with -1 becouse "i" means imaginary number... i^2=-1

OpenStudy (anonymous):

Lol don't say that i equals to what i said up there if you square i, what is its value?

OpenStudy (anonymous):

Yep! So go back to your question and solve it using this knowledge

OpenStudy (aaronandyson):

(x+9i)2 i is -1 as said by @OrthodoxMan

OpenStudy (aaronandyson):

is it (x + 9i)2 or (x + 9i)^2?

OpenStudy (anonymous):

the second one^ Let's see if she solves it Pretty sure she is done

OpenStudy (aaronandyson):

yep shes done i guess

OpenStudy (anonymous):

Apply the square to the i as well

OpenStudy (anonymous):

Remember what i^2 = ...

OpenStudy (anonymous):

NO DONT GIVE UP LOOL Treat i as a variable Substitute -1 into i Hence you must do x^2 + 18(-1)

OpenStudy (aaronandyson):

WHAT ON EARTH IS THIS?

OpenStudy (anonymous):

MOVE AWAY BHUMI WE BANISH YOU

OpenStudy (anonymous):

that was pretty rude...oh well

OpenStudy (anonymous):

Because you're smart You need to keep practising In no time, you'll be better than us

OpenStudy (anonymous):

If you stop complaining and let me help you I can go to sleep :P

OpenStudy (aaronandyson):

lol sleep then i can try to help

OpenStudy (anonymous):

Haha alright thanks man Make sure she finishes all of her questions

OpenStudy (aaronandyson):

yep i will

OpenStudy (aaronandyson):

oh,well shes offline -.-

OpenStudy (anonymous):

-.- guess we can both get off goodnight

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