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Mathematics 8 Online
OpenStudy (anonymous):

I NEED HELP!!! MEDAL AND FAN REWARD!!! See post for questions

OpenStudy (anonymous):

whats the question

OpenStudy (anonymous):

I need help with creating the following: One function, f(x), with two real rational solutions One function, g(x), with two real irrational solutions One function, h(x), with two complex solutions Explain how you know these functions meet each condition

OpenStudy (anonymous):

I promise I'm not trying to cheat or anything I just need serious help. I can't figure this out! @ranga @Captain_Page_Turner @Calliope

OpenStudy (anonymous):

@ganeshie8

OpenStudy (ranga):

Pick two rational numbers say 2 and 3 Then f(x) = (x-2)(x-3) will be a function with two real rational roots because if I put x =2 or x = 3 f(x) will become 0 and therefore 2 and 3 are the roots. You can multiply it out and f(x) = x^2 - 5x + 6

OpenStudy (anonymous):

Okay, that makes some sense

OpenStudy (ranga):

For the general quadratic function ax^2 + bx + c to have irrational roots, the discriminant must NOT be a perfect square. Discriminant is: b^2 - 4ac Choose a, b and c such that they are not a perfect square. Let a = 1, you choose b and c.

OpenStudy (anonymous):

a=1, b = 7, c=2? @ranga

OpenStudy (ranga):

And the discriminant should be positive and not a perfect square for real, irrational roots.

OpenStudy (anonymous):

you could use the same function for all three requirements by multiplying together two real rational roots, two real irrational roots, and ± an imaginary root.

OpenStudy (ranga):

Yes, a=1, b = 7, c=2 will do the job.

OpenStudy (anonymous):

how would you suggest i go about the imaginary root part? @Peter14

OpenStudy (ranga):

g(x) = x^2 + 7x + 2

OpenStudy (ranga):

For imaginary solutions, make the discriminant negative.

OpenStudy (anonymous):

right thats what i put @ranga

OpenStudy (ranga):

make b^2 - 4ac negative let a = 1, you choose b and c

OpenStudy (anonymous):

multiply together (x+ai) (x-ai) to make a simple function that fulfils the requirements

OpenStudy (anonymous):

okay so the discriminant is negative for the third and i just have to decide what i want b and c to be? does it matter if they are rational or irrational?

OpenStudy (ranga):

choose integers but make b^2 - 4ac negative. a= 1, b = 2, c = 3 will do the job

OpenStudy (anonymous):

or h(x)=x^2 + 1

OpenStudy (anonymous):

okay @ranga

OpenStudy (anonymous):

thank you @ranga and @Peter14

OpenStudy (ranga):

you are welcome.

OpenStudy (anonymous):

you're welcome

OpenStudy (anonymous):

any other questions? or are you going to close the question now?

OpenStudy (anonymous):

I will be closing it. but ill message you if i have any @Peter14

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