If the derivative of the function f(x)= m x +2 n x+1 vanishes at x=2 , then what is the value of m+8 n ?

Step-by-step solution

aligned & F ( x )= m x +2 nx +1 & f ^ ( x )= - m x ^2 +2 n aligned given that f^ (2)=0 aligned & - m (2)^2 +2 n =0 & - m +8 n =0 aligned 8 n - m =0 ...(i) from equation we can't find value of m+8 n .