Q. 82

Question

Write a delta–epsilon proof that shows that the function f(x)=2x+1 is continuous at x=5. (This exercise depends on Section 1.3.) 

Step-by-Step Solution

Verified
Answer

Hence we proved limx5(2x+1)=11

1Step 1. Given Information

We are given the function f(x)=2x+1 is continuous at x=5 and we need to write a delta–epsilon proof. 

2Step 2. Delta–epsilon proof

f(x)=2x+1c=5L=2(5)+1=10+1=11

For ε>0, δ=ε2,

If 0<x-5<δ we have,

2x+1-11=2x-10=2x-5<2δ=2ε2=εlimx52x+1=11