Question

Given the function f(x) = x2 and k = –1, which of the following represents a function opening downward

a. f(x) + k
b. kf(x)
c. f(x + k)
d. f(kx)

Answer 1

Answer=B

B is the only function with a negative slope.

kf(x)=-1(x^2) (the slope is negative so the parabola opens downward)

Answer 2

Answer : B

Given the function f(x) = x^2 and k = –1

We plug in f(x)  and k values and check

a. f(x) + k  ----> $x^2 -1$ , the value of 'a' is +1  . so it open upward

b. kf(x)  ----> $-1x^2$ , the value of 'a' is -1  . so it open downward

c. f(x + k) ----> $(x-1)^2$ , the value of 'a' is +1  . so it open upward

d. f(kx)----> $(-1x)^2=x^2$ , the value of 'a' is +1  . so it open upward

Option B is our final answer