Answer:
g(x) = 12*x^2 + 8
Step-by-step explanation:
For a function f(x), a vertical stretch of scale factor k is defined as:
g(x) = k*f(x)
In this case, we know that f(x) = 3*x^2 + 2
And the function g(x) is the function f(x) vertically stretched by a factor of 4, then we have k = 4
and:
g(x) = 4*f(x)
Replacing by the actual function, we get
g(x) = 4*(3*x^2 + 2)
g(x) = 4*3*x^2 + 4*2
g(x) = 12*x^2 + 8