Please Help me Trigometry question easy!!! (10 points best answer)
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Please Help me Trigometry question easy!!! (10 points best answer)

[From: ] [author: ] [Date: 11-11-29] [Hit: ]
-if its so easy , then why dont you just do it yourself ?......
Thanks to everyone who answers
Here's the problem.

The question asks to find all the roots of the following problem:
y= x cubed minus 18x

my teacher used the difference of squares to find the roots but it was to the 4th, so I got it, but with the cubed, I do not understand. Thank you , thank you, so much. Happy Holidays!!!!!!!!

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y = x³ - 18x

roots are when y = 0

0 = x³ - 18x

factor out x

0 = x(x²-18)

because of the multiplicative property of 0, this gives us 2 equations: x = 0 and x²-18 = 0

x = 0 is already solved

x²- 18 = 0

add 18 to each side

x² = 18

take the root of each side and factor 9 out of the radical

x = ± 3√2

Solution: x = {3√2, -3√2, 0}

hope I helped

-
Express as y=x(x^2 -18) and take it from there.

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if its so easy , then why dont you just do it yourself ?
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