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Mathematics 8 Online
OpenStudy (lovelyharmonics):

factor theorem

OpenStudy (lovelyharmonics):

Use the Factor Theorem to determine whether the first polynomial is a factor of the second polynomial. x - 5; 3x2 + 5x + 50

OpenStudy (reemii):

if yes, that would mean that ... is a zero. just check if ... is indeed a zero.

OpenStudy (lovelyharmonics):

3(0)^2+5(0)+50 0+0+50 50 so no?

OpenStudy (anonymous):

don't replace \(x\) by \(0\). replace \(x\) by \(5\)

OpenStudy (anonymous):

in any case, \(5\) cannot be a zero of \( 3x^2 + 5x + 50 \) because all the coefficients are positive

OpenStudy (lovelyharmonics):

okay... so 3(5)^2+5(5)+50 75+25+50=150

OpenStudy (campbell_st):

the factor theorem basically says if (x -5) is a factor then x = 5 is a zero so you need to find f(5) if f(5) = 0 then you know (x -5) is a factor

OpenStudy (lovelyharmonics):

we arnt trying to find 0's though....

OpenStudy (anonymous):

that is clear right? if all the coefficients are positive, and you replace \(x\) by a positive number, then everything is positive, so it cannot be zero zeros mean \[f(x)=0\] not \(f(0)\)

OpenStudy (anonymous):

for example the zeros of \(x^2-4\) are \(2\) and \(-2\) not \(0^2-4=-4\)

OpenStudy (anonymous):

in any event \( f(x)=3x^2 + 5x + 50\) lives entirely above the \(x\) axis and has no zeros does not factor with real numbers

OpenStudy (reemii):

according to the thm: (x-5) is a factor of the polynomial IFF 5 is a zero of the polynomial. 5 is not a zero => x-5 is not a factor of the polynomial.

OpenStudy (campbell_st):

ok... so given a polynomial e.g \[y = x^2 + 5x + 6 \] then it factors to \[y = (x + 2)(x + 3)\] to find the values of x that may y = 0 you need to solve \[x + 2 = 0... and.... x + 3 = 0\] so the solutions are x = -2, and x = -3 substitute these values into the original equation and you'll find f(-2) = 0....... and f (-3) = 0 so therefore (x +2) and (x + 3) are factors...

OpenStudy (lovelyharmonics):

lol okay thanks you guys

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