[填空题]
Consider the function . g2;r v8d6yvkrbcw8f h/d ne :.b8kbpf(X)=2x$^4$ + 1.
1.Find f′(x)=ax$^3$, a= .
2.Find the gradient of the graph of f at x=−1.
f′(-1)=- .
3.Find the x-coordinate of the point at which the normal to the graph of f has a gradient of −8.
x=$\frac{a}{b}$, a= , b= .
