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DeadShot
 2 years 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?
DeadShot
 2 years 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?

This Question is Closed

tcarroll010
 2 years 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
 2 years ago
Best ResponseYou've already chosen the best response.0x^3 2.25x^2+2.25x^23x22.25x+2.25x3x15

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

tcarroll010
 2 years 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
 2 years 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
 2 years 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
 2 years ago
Best ResponseYou've already chosen the best response.0sqrt(5) is approx 2.25

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

tcarroll010
 2 years 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
 2 years ago
Best ResponseYou've already chosen the best response.0(x^25) (x3)=x^3  3x^2  5x + 15

tcarroll010
 2 years 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
 2 years 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
 2 years ago
Best ResponseYou've already chosen the best response.0so, it's x^3+3x^25x15?

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

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

tcarroll010
 2 years 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
 4 months ago
Best ResponseYou've already chosen the best response.1x3 + 3x2  5x  15 is not the correct answer (just took the test)
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