Question

Use a graphing calculator, or another piece of technology, to find the zeros of the function f(x)=−2x^3+5x^2+1

What are the approximate zeros to the nearest tenth?

There may be more than one correct answer. Select all correct answers.

• x≈0.2
• x≈−0.2
• x≈1.7
• x≈−2.58
• x≈−1.7
• x≈2.58

Answer 1

Solution:

Graph of $f(x)=−2x^3+5x^2+1$ is:

Clearly, it intersects x-axis at only one point, so it has one real root, i.e. $x=2.575$

So, we get $x\approx 2.58$ only (option 6).