Q. f(x)=(2x+5)(x+3)(3x−10)(2x−8) has zeros at x=−3,x=−25,x=310, and x=4.What is the sign of f on the interval −25<x<4 ?Choose 1 answer:(A) f is always positive on the interval.(B) f is always negative on the interval.(C) f is sometimes positive and sometimes negative on the interval.
Factor Analysis: To determine the sign of f(x) on the interval, we need to look at the sign of each factor in the given interval.
Sign Determination: For the factor (2x+5), when x is between −25 and 4, this factor is positive because 2x+5 is greater than zero for all x in this interval.
Factor (2x+5): For the factor (x+3), when x is between −25 and 4, this factor is also positive because x+3 is greater than zero for all x in this interval.
Factor (x+3): For the factor (3x−10), when x is between −25 and 4, this factor is negative because 3x−10 is less than zero when x is less than 310, which is part of our interval.
Factor (3x−10): For the factor (2x−8), when x is between −25 and 4, this factor is negative because 2x−8 is less than zero when x is less than 4, which is part of our interval.
Factor (2x−8): Since we have two negative factors and two positive factors, the negatives will cancel each other out, and the overall sign of f(x) on the interval will be positive.