29. Approximate the greatest real root of f (x) = x^3 – 2x-5 to the nearest tenth.?

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29. Approximate the greatest real root of f (x) = x^3 – 2x-5 to the nearest tenth.?

A. 1.8
B. 2.0
C. 2.1
D. -0.6

2007-06-02 06:59:40 · 3 answers · asked by Tayyaba S 1 in Science & Mathematics ➔ Mathematics

3 answers

Let study f(x) f´(x)= 3x^2-2 = 0
x=+-sqrt(2/3)
signf´ ++++++(-sqrt2/3)---------(sqrt2/3)++++++++
f(-sqrt2/3)<0
f(sqrt2/3)<0
At x=2 f(2) is still negativ.so the root is greater than 2
f(2.2)>0
Taking the midpoint x=2.1 (B)

2007-06-02 07:17:08 · answer #1 · answered by santmann2002 7 · 0⤊ 0⤋

Plug all of the values in for x and see which one yields an answer closest to zero.

2007-06-02 14:03:32 · answer #2 · answered by abcd098 2 · 0⤊ 0⤋

Are you allowed to use a graphing calculator on this test?
If not, I'll wait to answer question #30.

2007-06-02 14:04:21 · answer #3 · answered by kickthecan61 5 · 0⤊ 0⤋