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Hi I need help solving the problem:
Find all the roots of the polynomial P(x)=4x311x2+2x+3

 Oct 28, 2024
 #2
avatar+1950 
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Let's see. The roots of a polynomial means that when we plug in x, we essentially get p(x) = 0. 

Thus, setting the polynomial to 0, we get the equation 4x311x2+2x+3=0

 

Now, we have to find factors. We could do this in two ways. We could first have

4x3+3x2+8x22x3=04x3+3x2+8x26x+4x3=0x2(4x3)+8x26x+4x3=0x2(4x3)+2x(4x3)+4x3=0x2(4x3)+2x(4x3)+1(4x3)=0(4x3)(x22x1)=0(4x3)(x22x1)=0

 

We could also test for factors. If we plug in 1, we get that P(1)=2 and plugging in 0 gets p(0)=3

Thus, the number must be in between 0 and 1. Testing 1/2, we get P(1/2)=1.75 so it must be in between 1/2 and 1. That's how we get 3/4. 

 

We can split these into two equations to find x. We have

4x3=0x22x1=0

 

Now, the second quadratic is now factorable over whole numbers, so we must use the quadratic equation. 

Using it, we get that 

x=1+2x=12

 

From the first equation, we know x = 3/4 as well. 

 

Thus, our final 3 answers are

x=34x=1+2x=12

 

 

Thanks! :)

 Oct 28, 2024
edited by NotThatSmart  Oct 28, 2024
edited by NotThatSmart  Oct 28, 2024

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