The document provides two examples of limits involving radicals. In the first example, the limit is evaluated as x approaches positive infinity and negative infinity. The limit is 1 as x approaches positive infinity, and -1 as x approaches negative infinity. In the second example, the limit is simplified by dividing and multiplying by the conjugate, and the limit is evaluated to be 0 as x approaches infinity.
7. Limits with Radicals
Example 1
Let’s consider the limit:
lim
x→∞
√
x2 + 1
x + 1
Here we have a radical.
We’re going to do something similar to our basic technique.
8. Limits with Radicals
Example 1
Let’s consider the limit:
lim
x→∞
√
x2 + 1
x + 1
Here we have a radical.
We’re going to do something similar to our basic technique.
So, we divide and multiply by x2 inside the radical symbol:
9. Limits with Radicals
Example 1
Let’s consider the limit:
lim
x→∞
√
x2 + 1
x + 1
Here we have a radical.
We’re going to do something similar to our basic technique.
So, we divide and multiply by x2 inside the radical symbol:
lim
x→∞
x2+1
x2 .x2
x + 1
10. Limits with Radicals
Example 1
Let’s consider the limit:
lim
x→∞
√
x2 + 1
x + 1
Here we have a radical.
We’re going to do something similar to our basic technique.
So, we divide and multiply by x2 inside the radical symbol:
lim
x→∞
x2+1
x2 .x2
x + 1
lim
x→∞
1 + 1
x2 x2
x + 1
15. Limits with Radicals
Example 1
lim
x→∞
1 + 1
x2 x2
x + 1
Here we have two cases to consider:
1. x < 0.
As we are taking a positive square root:
16. Limits with Radicals
Example 1
lim
x→∞
1 + 1
x2 x2
x + 1
Here we have two cases to consider:
1. x < 0.
As we are taking a positive square root:
lim
x→∞
(−x)
1 + 1
x2
x + 1
17. Limits with Radicals
Example 1
lim
x→∞
1 + 1
x2 x2
x + 1
Here we have two cases to consider:
1. x < 0.
As we are taking a positive square root:
lim
x→∞
(−x)
1 + 1
x2
x + 1
We can also write this as:
18. Limits with Radicals
Example 1
lim
x→∞
1 + 1
x2 x2
x + 1
Here we have two cases to consider:
1. x < 0.
As we are taking a positive square root:
lim
x→∞
(−x)
1 + 1
x2
x + 1
We can also write this as:
− lim
x→∞
1 + 1
x2
x+1
x
22. Limits with Radicals
Example 1
− lim
x→∞
1 + 1
x2
x+1
x
= − lim
x→∞
1 + 1
x2
1 + 1
x
Now, as we take the limit when x → +∞:
23. Limits with Radicals
Example 1
− lim
x→∞
1 + 1
x2
x+1
x
= − lim
x→∞
1 + 1
x2
1 + 1
x
Now, as we take the limit when x → +∞:
= − lim
x→∞
1 + 1
x2
1 + 1
x
24. Limits with Radicals
Example 1
− lim
x→∞
1 + 1
x2
x+1
x
= − lim
x→∞
1 + 1
x2
1 + 1
x
Now, as we take the limit when x → +∞:
= − lim
x→∞
1 +
U
0
1
x2
1 + 1
x
25. Limits with Radicals
Example 1
− lim
x→∞
1 + 1
x2
x+1
x
= − lim
x→∞
1 + 1
x2
1 + 1
x
Now, as we take the limit when x → +∞:
= − lim
x→∞
1 +
U
0
1
x2
1 +
¡
¡!
0
1
x
26. Limits with Radicals
Example 1
− lim
x→∞
1 + 1
x2
x+1
x
= − lim
x→∞
1 + 1
x2
1 + 1
x
Now, as we take the limit when x → +∞:
= − lim
x→∞
1 +
U
0
1
x2
1 +
¡
¡!
0
1
x
= −
√
1
1
= −1
27. Limits with Radicals
Example 1
− lim
x→∞
1 + 1
x2
x+1
x
= − lim
x→∞
1 + 1
x2
1 + 1
x
Now, as we take the limit when x → +∞:
= − lim
x→∞
1 +
U
0
1
x2
1 +
¡
¡!
0
1
x
= −
√
1
1
= −1
32. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
33. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
34. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
= lim
x→∞
1 + 1
x2
x+1
x
35. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
= lim
x→∞
1 + 1
x2
x+1
x
= lim
x→∞
1 + 1
x2
1 + 1
x
36. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
= lim
x→∞
1 + 1
x2
x+1
x
= lim
x→∞
1 +
U
0
1
x2
1 + 1
x
37. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
= lim
x→∞
1 + 1
x2
x+1
x
= lim
x→∞
1 +
U
0
1
x2
1 +
¡
¡!
0
1
x
38. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
= lim
x→∞
1 + 1
x2
x+1
x
= lim
x→∞
1 +
U
0
1
x2
1 +
¡
¡!
0
1
x
= 1
39. Limits with Radicals
Example 1
Now the second case:
2. x 0.
lim
x→∞
1 + 1
x2 x2
x + 1
We take the positive square root:
lim
x→∞
(x)
1 + 1
x2
x + 1
= lim
x→∞
1 + 1
x2
x+1
x
= lim
x→∞
1 +
U
0
1
x2
1 +
¡
¡!
0
1
x
= 1
48. Limits with Radicals
Example 2
Let’s now consider the limit:
lim
x→∞
x2 + 1 − x2 − 1
This limit is different, but easily solved.
49. Limits with Radicals
Example 2
Let’s now consider the limit:
lim
x→∞
x2 + 1 − x2 − 1
This limit is different, but easily solved.
We just need to divide and multiply by the conjugate:
50. Limits with Radicals
Example 2
Let’s now consider the limit:
lim
x→∞
x2 + 1 − x2 − 1
This limit is different, but easily solved.
We just need to divide and multiply by the conjugate:
lim
x→∞
x2 + 1 − x2 − 1 .
√
x2 + 1 +
√
x2 − 1
√
x2 + 1 +
√
x2 − 1
51. Limits with Radicals
Example 2
Let’s now consider the limit:
lim
x→∞
x2 + 1 − x2 − 1
This limit is different, but easily solved.
We just need to divide and multiply by the conjugate:
lim
x→∞
x2 + 1 − x2 − 1 .
√
x2 + 1 +
√
x2 − 1
√
x2 + 1 +
√
x2 − 1
Doing the algebra in the numerator:
52. Limits with Radicals
Example 2
Let’s now consider the limit:
lim
x→∞
x2 + 1 − x2 − 1
This limit is different, but easily solved.
We just need to divide and multiply by the conjugate:
lim
x→∞
x2 + 1 − x2 − 1 .
√
x2 + 1 +
√
x2 − 1
√
x2 + 1 +
√
x2 − 1
Doing the algebra in the numerator:
lim
x→∞
√
x2 + 1
2
−
√
x2 − 1
2
√
x2 + 1 +
√
x2 − 1