I have a quadratic linear regression of the form:
y = B0 + B1x^2
I need to do a hypothesis test that the marginal effect of an additional unit of x at a specific level of x is greater than 100.
I know that the marginal effect of x at any point is given by 2*B1*x. However, the regression output provides the standard errors for B1, not 2*B1*x.
To calculate the new standard error, do I simply multiply the standard errors by (2*x)^2?