Given g(x) is the integral from a to x of f(t) dt, we were able to derive that g'(x) = 1/h integral from x to x+h of f(t) dt. By the extreme value theorem there exists a min m and max M on [x,x+h] such that f(u) = m and f(v) = M and f(u)h<= integral x to x+h f(t) dt <= f(v)h (by properties of integrals). Dividing by h we get f(u)<= (g(x+h)- g(x)) / h <= f(v) by substitution. Here is where I'm confused, the text says if we let h--> 0 then u --> x and v--> x since u and v lie in [x,x+h]. I'm not understanding how u--> x and v--> x.
I'm self studying Stewart calculus and I'm working through the proof of FTC part 1. I'm stuck on a line in the proof that is preventing me from preceding.
Given g(x) is the integral from a to x of f(t) dt, we were able to derive that g'(x) = 1/h integral from x to x+h of f(t) dt.
By the extreme value theorem there exists a min m and max M on [x,x+h] such that f(u) = m and f(v) = M and f(u)h<= integral x to x+h f(t) dt <= f(v)h (by properties of integrals).
Dividing by h we get f(u)<= (g(x+h)- g(x)) / h <= f(v) by substitution.
Here is where I'm confused, the text says if we let h--> 0 then u --> x and v--> x since u and v lie in [x,x+h]. I'm not understanding how u--> x and v--> x. See 3rd image below, text is a red box.
Step by step
Solved in 2 steps