Question 1189470: A function 𝑓(𝑥) = 𝑥^3 + 2𝑥 − 1 has a zero within (0,1). Find the interval that
the zero exists.
(A) (0.1, 0.3) (B) (0.4, 0.5) (C) (0.6, 0.7) (D) (0.7, 0.9) (E) none of the
above.
Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20059)   (Show Source):
You can put this solution on YOUR website!
Are you allowed to use a graphing calculator, or is your teacher
stuck back in the eighties? If you can use a graphing calculator,
then use it to find the approximate solution, 0.4533977, and then
you'll know the answer is (B).
Otherwise it's a bunch of trial and error, substituting both numbers
in to see which choice gives you two numbers with different signs.
Edwion
Answer by ikleyn(52800)  (Show Source):
You can put this solution on YOUR website! .
I just gave crystally clear discussion and the solution to this problem under the link
https://www.algebra.com/algebra/homework/Polynomials-and-rational-expressions/Polynomials-and-rational-expressions.faq.question.1189314.html
https://www.algebra.com/algebra/homework/Polynomials-and-rational-expressions/Polynomials-and-rational-expressions.faq.question.1189314.html
Don't know what was the need to post it again . . .
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As presented in the post, the " problem " is mathematically and educationally meaningless.
To be meaningful, it should be re-edited.
The right formulation is THIS :
A function 𝑓(𝑥) = 𝑥^3 + 2𝑥 − 1 has a zero within (0,1). Find the interval where zero exists, if you only have
a calculator, which allows you to calculate the values of the function in given points, and nothing else.
(A) (0.1, 0.3) (B) (0.4, 0.5) (C) (0.6, 0.7) (D) (0.7, 0.9) (E) none of the above.
I am 99% sure that somewhen in the past this problem existed (and was created) in this my last formulation,
but after that it was copy-pasted many times from one web-site to another by people who did not understand its meaning,
(by mathematically incompetent people) and, as a result of such activity in the Internet, the meaning was lost irrevocably.
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