Question

6.Using complete sentences, explain how to find the zeros of the function f(x) = 2x^3 – 9x + 3. (2 points)

Answer 1

trial and error ...

Answer 2

if there is a certain section of math that you are doing, then it prolly wants you to be more exacting. but without knowing what you are working with, trial and error is actually a valid method

Answer 3

im doing graphing polynomial functions

Answer 4

hmmm, is that spose to be a ^3 up there? or a ^2

Answer 5

3

Answer 6

without knowing some calculus, anything over ^2 is a bit challenging

Answer 7

its algerbra 2

Answer 8

2x^3 – 9x + 3 = 0

2x^3 – 9x = -3

x(2x^2 – 9) = -3

x (sqrt(2)x-3) (sqrt(2)x+3) = -3

factoring is usually helpful, but there is an art to it

Answer 9

try x=0; f(0) = 3
try x=1; f(1) = -4

so it has to cross someplace between 0 and 1 at elast

Answer 10

since 2x^3 is a positive odd function this thing will at least behave like x^3



itll have at least 1 0, and at most 3



and from this vantage point we shold know itll look something like this

Answer 11

ok

Answer 12

we can try a larger value to see what gets us back above the line;

f(5) = 2(125) – 45 + 3 is greater than 0

f(3) = 2(27) – 27 + 3 is greater than 0

f(2) = f(5) = 2(8) – 18 + 3 = 1 is greater than 0

so there is another zero between 1 and 2