please help with it

Plug in to = B/M and tn = 1 to show that f(In) - 1(tn) = aB M IVf(In) |2 or f(In) - 1(tn) = allVf(In) |2 This then provides an underestimate for how much f(x) decreases in function value when taking one gradient descent step: i.e. aB (3) minta, HIVf( x)Il'sf(In) - f(In+1 )Suppose f(x) E C2, and satisfies: (1) ml = V'f(x)