To two decimal places, find the value of k that will make the function f(x) continuous everywhere. f of x equals the quantity 3x + k for x less than or equal to -4 and is equal to kx^2 - 5 for x greater than -4
11.00
-2.47
-0.47
None of these

Respuesta :

Given function is

[tex]f(x)=\left\{\begin{matrix}3x+k & x\leq -4 \\ kx^2-5 & x> -4\end{matrix}\right.[/tex]

now we need to find the value of k such that function f(x) continuous everywhere.

We know that any function f(x) is continuous at point x=a if left hand limit and right hand limits at the point x=a are equal.

So we just need to find both left and right hand limits then set equal to each other to find the value of k

To find the left hand limit (LHD) we plug x=-4 into 3x+k

so LHD= 3(-4)+k

To find the Right hand limit (RHD) we plug x=-4 into

[tex]kx^2-5[/tex]

so RHD= [tex]k(-4)^2-5[/tex]

Now set both equal

[tex]k(-4)^2-5=3(-4)+k[/tex]

[tex]16k-5=-12+k[/tex]

[tex]16k-k=-12+5[/tex]

[tex]15k=-7[/tex]

[tex]k=-\frac{7}{15}[/tex]

k=-0.47

Hence final answer is -0.47.