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 one year ago
Which of the following is a polynomial with roots  square root of 5, square root of 5, and 3 ? x3  2x2  3x + 6, x3 + 2x2  3x  6, x3  3x2  5x + 15, or x3 + 3x2  5x  15?
 one year ago
Which of the following is a polynomial with roots  square root of 5, square root of 5, and 3 ? x3  2x2  3x + 6, x3 + 2x2  3x  6, x3  3x2  5x + 15, or x3 + 3x2  5x  15?

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tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3If you have roots of: a, b, and c your polynomial has the form: (x  a)(x  b)(x  c) = 0 Substitute a, b, and c for the given roots and multiply the expression out on the left side.

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0x^3 2.25x^2+2.25x^23x22.25x+2.25x3x15

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0simplified, it's x^33x^23x15, right?

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3You wouldn't even have to ask that last question because you have 4 choices and this choice is not even listed among them. Here's a hint on how to expand that expression I gave you: (x  a)(x  b)(x  c) = 0 [(x  a)(x  b)](x  c) = 0 [x^2  (a + b)x + ab](x  c) = 0 [x^2  (a + b)x + ab]x  [x^2  (a + b)x + ab]c = 0

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0[x^2(2.25+2.25)x + (2.25)*2.25]x[x^2(2.25+2.25)x + (2.25)*2.25]3=0

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3Where are you getting +2.25 from? Neither has anything to do with sqrt(5).

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0sqrt(5) is approx 2.25

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3You don't want to be working with approximations here.

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3I would suggest evaluating the following first: [x  sqrt(5)][x + sqrt(5)] That correspond to the leftmost factors. Get that down to a trinomial.

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0(x^25) (x3)=x^3  3x^2  5x + 15

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3The third root is "3", so you have: [x  (3)] or (x + 3) for that third factor. I think that's where you having your trouble. When you subtract a negative, it's like adding a positive.

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3So, taking up from where you were writing: (x^2  5)(x + 3) = 0 And then expand that. You are very close to your answer now.

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0so, it's x^3+3x^25x15?

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3Yes! Excellent! Just remember about subtracting negatives and you will be ok.

DeadShot
 one year ago
Best ResponseYou've already chosen the best response.0Okay, Thanks for the help!

tcarroll010
 one year ago
Best ResponseYou've already chosen the best response.3You're welcome! Good luck to you in all of your studies and thx for the recognition! @DeadShot

malice
 one month ago
Best ResponseYou've already chosen the best response.0x3 + 3x2  5x  15 is not the correct answer (just took the test)
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