Question

Approximate to the nearest tenth the real zeros of f(x) = –5x3 + 9x2 + 12x + 2.

answers:
The zeros are approximately 0.2, 0.7, and 2.7.
The zeros are approximately –2.7, –1.7, and 0.2.
The zeros are approximately –0.2, –0.7, and 2.7.
The zeros are approximately –0.5, –0.7, and 1.7.

Answer 1

the answer is C

Explanation:

Answer 2

Correct answer is C.


`-5 x^3 + 9 x^2 +12 x+ 2=(-5 x-1) \left(x^2-2 x-2\right) \\ \\\left\{-(1)/(5),1-√(3),1+√(3)\right\}\to \{-0.2,-0.732051,2.73205\}`

Or check if f(0.2) = 0 to eliminate A and B.
Then check if f(-0.5) = 0 to eliminate D.