Questions on Functions with Solutions
Several questions on functions are presented and their detailed solutions discussed. The questions cover a wide range of concepts related to functions such as definition, domain, range, evaluation, composition and transformations of the graphs of functions.
Question 1: Is the graph shown below that of a function?
graph of question 1
Solution to Question 1:
Vertical line test: A vertcal line at x = 0 for example cuts the graph at two points. The graph is not that of a function.
Question 2: Does the equation
y 2 + x = 1
represents a function y in terms of x?
Solution to Question 2:
Solve the above equation for y
y 2= 1 - x
y = + SQRT(1 - x) or y = - SQRT(1 - x)
For one value of x we have two values of y and this is not a function.
Question 3: Function f is defined by
f(x) = - 2 x 2 + 6 x - 3
find f(- 2).
Solution to Question 3:
Substitute x by -2 in the formula of the function and calculate f(-2) as follows
f(-2) = - 2 (-2) 2 + 6 (-2) - 3
f(-2) = -23
Question 4: Function h is defined by
h(x) = 3 x 2 - 7 x - 5
find h(x - 2).
Solution to Question 4:
Substitute x by x - 2 in the formula of function h
h(x - 2) = 3 (x - 2) 2 - 7 (x - 2) - 5
Expand and group like terms
h(x - 2) = 3 ( x 2 - 4 x + 4 ) - 7 x + 14 - 5
= 3 x 2 - 19 x + 7
Question 5: Functions f and g are defined by
f(x) = - 7 x - 5 and g(x) = 10 x - 12