Write the polynomial in factored form as a product of linear factors f(r)=r^3-9r^2+17r-9
1 answer:
Answer:
f(r) = (x -1)(x -4+√7)(x -4-√7)
Step-by-step explanation:
The signs of the terms are + - + -. There are 3 changes in sign, so Descartes' rule of signs tells you there are 3 or 1 positive real roots.
The rational roots, if any, will be factors of 9, the constant term. The sum of coefficients is 1 -9 +17 -9 = 0, so you know that r=1 is one solution to f(r) = 0. That means (r -1) is a factor of the function.
Using polynomial long division, synthetic division (2nd attachment), or other means, you can find the remaining quadratic factor to be r^2 -8r +9. The roots of this can be found by various means, including completing the square:
r^2 -8r +9 = (r^2 -8r +16) +9 -16 = (r -4)^2 -7
This is zero when ...
(r -4)^2 = 7
r -4 = ±√7
r = 4±√7
Now, we know the zeros are {1, 4+√7, 4-√7), so we can write the linear factorization as ...
f(r) = (r -1)(r -4 -√7)(r -4 +√7)
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<em>Comment on the graph</em>
I like to find the roots of higher-degree polynomials using a graphing calculator. The red curve is the cubic. Its only rational root is r=1. By dividing the function by the known factor, we have a quadratic. The graphing calculator shows its vertex, so we know immediately what the vertex form of the quadratic factor is. The linear factors are easily found from that, as we show above. (This is the "other means" we used to find the quadratic roots.)
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a) 2.5 shots
b) 59.4 shots
c) 4.87 shots
Step-by-step explanation:
Probability of making the shot = 0.6
Probability of missing the shot = 0.4
a) The expected number of shots until the player misses is given by:
The expected number of shots until the first miss is 2.5
b) The expected number of shots made in 99 attempts is:
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c) Let "p" be the proportion shots that the player make, the standard deviation for n = 99 shots is:
The standard deviation is 4.87 shots.
The perimeter for this case is given by:
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We equal zero and clear x:
Then, the other dimension is given by:
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