evaluating piecewise functions

G

Guest

Guest
I was given the function f(x) = { 3/4x if x>-4 and -1 + x^2 if x</=-4.

The question said to evaluate at the specified values of the independent variable and simplify.

The values given were (a) f(-4) (b) f(0) (c) f(1) and (d) f(-4.2).

This is probably really easy, but I have no idea what to do. I know you plug those numbers in for x, but in the first one it must be greater than -4 and (a) is -4. I'm just really confused, and I know it's probably something I should have gotten right away.

Please help me. Thanks!
 
To find the value of a piecewise function, take the value of x, figure out which part of the formula this fits into, plug the value into that part of the formula, and simplify. For instance, your given function is divided into one formula for x < -4 and another for x > -4. For f(0), you have to figure out which formula to use. Is zero bigger or smaller than negative four? Use the formula that goes with that. For x = -4, you have to go with the formula that goes with "or equal to".

Eliz.
 
Hello, ashleyslo!

I was given the function f(x) = { (3/4)x . if x > -4
. . . . . . . . . . . . . . . . . . . . . . .{ x<sup>2</sup> - 1 . if x <u><</u> -4

Evaluate at the specified values of the independent variable and simplify.

The values given were: .(a) f(-4), (b) f(0), (c) f(1), and (d) f(-4.2).
Make a number-line "picture" of what they've told us.

. . . . . . . . . . . -4] . . . . . . .0
. . . . - - - - - - - * - - - - - - + - -
. . ._________/ . \__________
. . . . use . . . . . . . . . . . use
. f(x) = x<sup>2</sup> - 1 . . . . . f(x) = (3/4)x


. . . Got it?
 
Top