Final answer:
To find the value of f(-5/3), substitute x = -5/3 into the given function f(x), simplify the expression, and find the value of the fraction.
Step-by-step explanation:
To find the value of f(-5/3), we need to substitute x = -5/3 into the function f(x) = -(2/7)x + (3/5)x^2.
So, f(-5/3) = -(2/7)(-5/3) + (3/5)(-5/3)^2.
Simplifying this expression, we get f(-5/3) = 10/21 + 9/5. Now, we need to find a common denominator and add these fractions together, giving us f(-5/3) = (50 + 189)/105 = 239/105.