3) f(x) = -2x2(x - 2)3(x + 4)4(x - 5)
The degree of a polynomial is the number of times that the variable (the 'x') is used as a factor.
in x2 = 2 times
in (x - 2)3 = 3 times
in (x + 4)4 = 4 times
in (x - 5) = 1 time
Total: 2 + 3 + 4 + 1 = 10 times <-- degree = 10
End behavior: What happens at the far left-end of the graph and at the far right-end of the graph.
For left-end behavior, place a "large" negative number (such as -10000) into each factor and see if the factor
becomes positive or negative:
-2 is negative
x2 is positive
(x - 2)3 is negative
(x + 4)4 is positive
(x - 5) is negative
Multiplying together, the answer is negative; so at the far left-end of the graph, the y-value will be negative;
so the graph starts at the lower-left end.
For right-end behavior, place a large positive number (such as 10000) into each factor and see if the factor
is positive or negative:
-2 is negative
x2 is positive
(x - 2)3 is positive
(x + 4)4 is positive
(x - 5) is positive
Multiplying together, the answer is negative; so at the far right-end of the graph, the y-value will be negative;
so the graph ends at the lower-right end.
Zeros occur at the x-values that make the factors zero.
x2 zero at 0
(x - 2)3 zero at 2
(x + 4)4 zero at -4
(x- 5) zero at 5
Bounces or pass through: the graph bounces at a zero that has an even degree, passes through at a zero that
has an odd degree.
x2 bounces at 0
(x - 2)3 passes through at 2
(x + 4)4 bounces at -4
(x - 5) passes through at 5
4) f(x) = 3x7 - 48x5
First, factor this: f(x) = 3x7 - 48x5 = 3x5(x2 - 16) = 3x5(x + 4)(x - 4)
Now, analyze this as problem 4) was analyzed.