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i dont understand how to do this
use descartes rule of signs to describe the root of
h(x)=4x^45x^3+2x^2x+5
 one year ago
 one year ago
i dont understand how to do this use descartes rule of signs to describe the root of h(x)=4x^45x^3+2x^2x+5
 one year ago
 one year ago

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richywBest ResponseYou've already chosen the best response.1
\[h(x)=4x^45x^3+2x^2x+5\]how many times does it change signs?
 one year ago

richywBest ResponseYou've already chosen the best response.1
i see 4 now do it for \(h(x)\)...
 one year ago

pinkdollbaby1234Best ResponseYou've already chosen the best response.0
okay so what do you mean by that solve for h?
 one year ago

richywBest ResponseYou've already chosen the best response.1
no \[h(x)=4(x)^45(x)^3+2(x)^2(x)+5\]Now simplify that, and then count the sign changes.
 one year ago

pinkdollbaby1234Best ResponseYou've already chosen the best response.0
oh okay so i would plug in 4 for x since it changes four times or is im wrong again?
 one year ago

richywBest ResponseYou've already chosen the best response.1
yeah you are wrong. this is what you should get.\[h(x)=4x^4+5x^3+2x^2+x+5\]Now how many times does the sign change places there?
 one year ago

pinkdollbaby1234Best ResponseYou've already chosen the best response.0
the sign doesnt change anymore cuz all are equal?
 one year ago

richywBest ResponseYou've already chosen the best response.1
yup so you can conclude that there are no negative roots, and either 4, 2 or 0 positive roots. You also know that there are 4 roots total. so you can either have 4 positive real and 0 complex, 2 and 2, or 0 real positive roots and 4 complex roots.
 one year ago

pinkdollbaby1234Best ResponseYou've already chosen the best response.0
omg thay seem soo simple i have to practice on this more but thankyou so much u help me understand it a bit
 one year ago

richywBest ResponseYou've already chosen the best response.1
yup no worries! And in this case that is all it can tell you. Sometimes it can tell you exactly how many of each there are, but sometimes it gives you a few options. It is still useful though because you can use it before you use other methods to get an idea what you are looking for...
 one year ago
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