posted by james on .
use the intermediate value theorem to show that f(x) has a zero in the given interval. f(x) = -x^5 -2x^4 + 5x^3 + 4; [-0.9, -0.8]
f(-.9) = -.367
f(-.8) = +.948
since f is continuous, it must assume all values between -.367 and +.948 on the interval [-.9,-.8].
That includes f(x) = 0.