#perfect square trinomial help

85 messages ยท Page 1 of 1 (latest)

pliant moth
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what do I factor out of $$\left(\frac{1}{9}x^4+\frac{1}{4}\right)\left(\frac{1}{4}+\frac{9}{16}x^{-4}\right)$$ to get a perfect square?

brave kilnBOT
stiff viperBOT
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jarker

pliant moth
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like in $(ax+b)^2$ form

stiff viperBOT
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jarker

pliant moth
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oh come on guys you know you wanna factor the perfect square trinomial :))))

stiff viperBOT
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adonhs

pliant moth
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can you walk me through the thought process. that is bs. how are you suppose to just visualize that on the spot. these math problems just skip over everything like it's second nature or something

pliant moth
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be honest, did you use an online calculator to factor it

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I'm really trying to figure out how you would go about this realistically in an exam scenario.

sullen crystal
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the audacity lol

pliant moth
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you seriously converted the whole equation to that form in your head then. Like no shame just want to know how you did it

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The stuff you wrote, I believe

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but you first rewrote it in a different form. that's what I'm talking about.

sullen crystal
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you can simply multiply it out like on the 2nd step

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you would get $\frac{1}{36}x^4 + \frac{1}{16} + \frac{1}{16} + \frac{9}{64x^4}$

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i'll write it in latex but it's a matter of 30sec expanding

stiff viperBOT
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adonhs

sullen crystal
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just multiplying out

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then you can do the same trick as yesterday

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also notice 9 and 64 can be written as squares

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and the x too

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and 36 too

pliant moth
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how is it not $$\frac{1}{36}x^4+\frac{1}{8}+\frac{9}{64x^4}$$

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wait that's the same thing lol

sullen crystal
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9 and x^4 cancels so we remain with 1/16

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then 1/4 * 1/4 = 1/16

stiff viperBOT
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jarker

sullen crystal
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and 1/4 * (9/16)x^-4 = (9/64)x^-4

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like 4 * 16 = 16 + 16 = 32 and nother 16 + 16 = 32 so we get 64

pliant moth
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$$\left(\frac{1}{6}x^2+\frac{3}{8x^2}\right)^2 = \frac{1}{36}x^4+\frac{1}{8}+\frac{9}{64x^4}$$

stiff viperBOT
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jarker

sullen crystal
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i also assumed that those tasks are made to be solvable this way and that you dont need to use "complete the square" technique

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1/8 = 2/16

pliant moth
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ah

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lol

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It's still not correct. here I'll give you the original trinomal

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maybe I grouped it wrong.

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$$\frac{1}{9}x^4+\frac{1}{2}+\frac{9}{16}x^{-4}$$

stiff viperBOT
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jarker

pliant moth
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I just split the 1/2 into 1/4 + 1/4

sullen crystal
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this yours or solution?

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ah ok

pliant moth
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this is the original trinomal

sullen crystal
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ok

pliant moth
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oh I fd up big time huh

pliant moth
sullen crystal
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$$\bigg(\frac{1}{3}x^2\bigg)^2+2\frac{1}{4}+\bigg(\frac{3}{4}x^{-2}\bigg)^2$$

stiff viperBOT
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adonhs

pliant moth
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what a waste of time

sullen crystal
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you are not an idiot

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shit happens

pliant moth
sullen crystal
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no

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why should i be disappointed?๐Ÿ˜…

pliant moth
sullen crystal
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to write it in terms of $a^2+2ab+b^2$

stiff viperBOT
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adonhs

pliant moth
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ah

sullen crystal
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you can also check 2ab

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$2\cdot \frac{1}{3}x^2\cdot \frac{3}{2}x^{-2} = 2\cdot \frac{1}{2} \neq \frac{1}{2}$

stiff viperBOT
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adonhs

sullen crystal
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ok you already said that it's wrong but to see my point of checking if 2ab adds up

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because we wrote it like 2 * 1/4

pliant moth
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omg that is so useful. thank you so much

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๐Ÿ’€

sullen crystal
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it's over for you

pliant moth
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so it's $\left(\frac{1}{3}x^2+\frac{3}{4}x^{-2}\right)^2$

stiff viperBOT
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jarker

pliant moth
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I'm literally in calc 2

sullen crystal
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no wait somethings off lemme see

sullen crystal
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it should have been 3/4

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it's correct congrats

pliant moth
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thanks again. sorry for being rude yesterday.

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