Find the following values if:
f(x) = 3x - 2 and g(x) = 4x2 + 5
c) f(-1) =
d) g(-3) =
e) f(5) - g(2) =
c)
f ( - 1 ) = 3 ∙ ( - 1 ) - 2 = - 3 - 2 = - 5
d)
g ( - 3 ) = 4 ∙ ( - 3 )² + 5 = 4 ∙ 9 + 5 = 36 + 5 = 41
e)
f ( 5 ) - g ( 2 ) = 3 ∙ ( 5 ) - 2 - [ 4 ∙ ( 2 )² + 5 ] =
15 - 2 - ( 4 ∙ 4 + 5 ) = 13 - ( 16 + 5 ) = 13 - 21 = - 8
To find the values of f(x) and g(x) at different inputs, you need to substitute the given input values into the given functions.
a) To find f(-1), substitute -1 into the function f(x) = 3x - 2:
f(-1) = 3(-1) - 2
= -3 - 2
= -5
Therefore, f(-1) = -5.
b) To find g(-3), substitute -3 into the function g(x) = 4x^2 + 5:
g(-3) = 4(-3)^2 + 5
= 4(9) + 5
= 36 + 5
= 41
Therefore, g(-3) = 41.
c) To find f(5) - g(2), first substitute 5 into the function f(x) = 3x - 2:
f(5) = 3(5) - 2
= 15 - 2
= 13
Then, substitute 2 into the function g(x) = 4x^2 + 5:
g(2) = 4(2)^2 + 5
= 4(4) + 5
= 16 + 5
= 21
Finally, subtract g(2) from f(5):
f(5) - g(2) = 13 - 21
= -8
Therefore, f(5) - g(2) = -8.