limit x->0 sin(2x)/x
Let's evaluate the limit of sin(2x)x when x0
The limit of 2x is 0 when x0
The limit of sin(2x) is 0 when x0
For sin(2x)x, the limit takes the indeterminate form 0/0 when x0
We look for a Taylor expansion of the expression: sin(2x)
Apply the Taylor development sin(A) + cos(A)·(X -A) of sin with X=2x around A=0 (order N=1)
sin(0) + cos(0)·(2x + 0)
0 + 2x
Let's restart using the Taylor expansion: 2x
2xx
2
So the limit of sin(2x)x is 2 when x0
Result:   2