Place value into a function

CONCEPTS

Tips

• The sign, number, and units are all affected when placing a value into an expression

• When placing a value into an expression, always use parentheses when the value is a negative number. This is especially important when that value is being subtracted (5 – (–9))…–9 is the value being inserted into the expression.

PRACTICE PROBLEMS

Question 1 What is f(4) given the functions,

f(x) = 2x + 1 when x < 4

f(x) = - 1/2 * x - 3 when x >= 4?

-- Answer -- -5

The 2nd function is used since x = 4

-1/2* (4) - 3 = -2 - 3 = -5

ACT PRACTICE PROBLEMS