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f(x)=(2x+5)(x+3)(3x-10)(2x-8) has zeros at 
x=-3,x=-(5)/(2),x=(10)/(3), and 
x=4.
What is the sign of 
f on the interval 
-(5)/(2) < 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.

f(x)=(2x+5)(x+3)(3x10)(2x8) f(x)=(2 x+5)(x+3)(3 x-10)(2 x-8) has zeros at x=3,x=52,x=103 x=-3, x=-\frac{5}{2}, x=\frac{10}{3} , and x=4 x=4 .\newlineWhat is the sign of f f on the interval \( -\frac{5}{2}

Full solution

Q. f(x)=(2x+5)(x+3)(3x10)(2x8) f(x)=(2 x+5)(x+3)(3 x-10)(2 x-8) has zeros at x=3,x=52,x=103 x=-3, x=-\frac{5}{2}, x=\frac{10}{3} , and x=4 x=4 .\newlineWhat is the sign of f f on the interval 52<x<4 -\frac{5}{2}<x<4 ?\newlineChoose 11 answer:\newline(A) f f is always positive on the interval.\newline(B) f f is always negative on the interval.\newline(C) f f is sometimes positive and sometimes negative on the interval.
  1. Factor Analysis: To determine the sign of f(x)f(x) on the interval, we need to look at the sign of each factor in the given interval.
  2. Sign Determination: For the factor (2x+5)(2x+5), when xx is between 52-\frac{5}{2} and 44, this factor is positive because 2x+52x+5 is greater than zero for all xx in this interval.
  3. Factor (2x+5)(2x+5): For the factor (x+3)(x+3), when xx is between 52-\frac{5}{2} and 44, this factor is also positive because x+3x+3 is greater than zero for all xx in this interval.
  4. Factor (x+3)(x+3): For the factor (3x10)(3x-10), when xx is between 52-\frac{5}{2} and 44, this factor is negative because 3x103x-10 is less than zero when xx is less than 103\frac{10}{3}, which is part of our interval.
  5. Factor (3x10)(3x-10): For the factor (2x8)(2x-8), when xx is between 52-\frac{5}{2} and 44, this factor is negative because 2x82x-8 is less than zero when xx is less than 44, which is part of our interval.
  6. Factor (2x8)(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)f(x) on the interval will be positive.

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