Evaluate the following limits: 1. lim (x3 - 27)/(x2 - 9) as x approaches 3. 2. lim (sqrt(x+2) - 3)/(x-7) as x approaches 7.
|Mathematics
Evaluate the following limits: 1. lim (x3 - 27)/(x2 - 9) as x approaches 3. 2. lim (sqrt(x+2) - 3)/(x-7) as x approaches 7.
ScanSolve AI Answer
5 steps
Answer
29
Welcome back ThegirlGodishelping🥰💙🫠 — missed you this week.
Here are the solutions to the limit problems.
We need to evaluate the limit:
limx→3x2−9x3−27
Step 1: Substitute x=3 into the expression.
32−933−27=9−927−27=00
This is an indeterminate form, so we need to simplify the expression.
Step 2: Factor the numerator and the denominator. Use the difference of cubes formula a3−b3=(a−b)(a2+ab+b2) and the difference of squares formula a2−b2=(a−b)(a+b).
x3−27=(x−3)(x2+3x+9)x2−9=(x−3)(x+3)
Step 3: Rewrite the limit with the factored expressions and cancel out the common term (x−3).
limx→3(x−3)(x+3)(x−3)(x2+3x+9)=limx→3x+3x2+3x+9
Step 4: Substitute x=3 into the simplified expression.
3+332+3(3)+9=69+9+9=627
Step 5: Simplify the fraction.
627=29
The limit is 29.
We need to evaluate the limit:
limx→7x−7x+2−3
Step 1: Substitute x=7 into the expression.
7−77+2−3=09−3=03−3=00
This is an indeterminate form, so we need to simplify the expression.
Step 2: Multiply the numerator and denominator by the conjugate of the numerator, which is x+2+3.
limx→7x−7x+2−3×x+2+3x+2+3
Step 3: Simplify the numerator using the difference of squares formula (a−b)(a+b)=a2−b2.
(x+2)2−32=(x+2)−9=x−7
Step 4: Rewrite the limit with the simplified numerator.
limx→7(x−7)(x+2+3)x−7
Step 5: Cancel out the common term (x−7).
limx→7x+2+31
Step 6: Substitute x=7 into the simplified expression.
7+2+31=9+31=3+31=61
The limit is 61.
We need to evaluate the limit:
limx→∞9x4+2x2−64x2−5x+1
Step 1: Identify the highest power of x in the denominator. Inside the square root, the highest power is x4, so x4=x2.
Step 2: Divide every term in the numerator and the denominator by x2. For terms inside the square root, divide by x4.
limx→∞x49x4+x42x2−x46x24x2−x25x+x21
Step 3: Simplify the terms.
limx→∞9+x22−x464−x5+x21
Step 4: Apply the limit. As x→∞, terms of the form xnc approach 0.
9+0−04−0+0=94
Step 5: Simplify the expression.
34
The limit is 34.
We need to evaluate the limit:
limx→0tan(3x)sin(5x)
Step 1: Rewrite tan(3x) in terms of sin(3x) and cos(3x).
limx→0cos(3x)sin(3x)sin(5x)=limx→0sin(3x)sin(5x)cos(3x)
Step 2: Rearrange the terms to use the special limit limu→0usinu=1.
limx→0(5xsin(5x)⋅sin(3x)3x⋅3x5x⋅cos(3x))
Step 3: Simplify the expression and apply the limit properties.
limx→0(5xsin(5x))⋅limx→0(sin(3x)3x)⋅limx→0(35)⋅limx→0(cos(3x))
Step 4: Evaluate each limit.
1⋅1⋅35⋅cos(0)=1⋅1⋅35⋅1=35
The limit is 35.
There are two problems labeled '5'. I will solve both.
First :
limx→0x21−cosx
Step 1: This is a standard limit. We can use the identity 1−cosx=2sin2(2x).
limx→0x22sin2(2x)
Step 2: Rearrange the terms to use the special limit limu→0usinu=1.
limx→02⋅xsin(2x)⋅xsin(2x)
Step 3: Multiply and divide by 21 for each xsin(2x) term.
limx→02⋅2x⋅2sin(2x)⋅2x⋅2sin(2x)
Step 4: Simplify and apply the limit.
limx→02⋅21⋅21⋅(2xsin(2x))⋅(2xsin(2x))=2⋅41⋅1⋅1=21
Alternatively, using L'Hôpital's Rule (since substituting x=0 gives 00):
Step 1: Apply L'Hôpital's Rule.
limx→0dxd(x2)dxd(1−cosx)=limx→02xsinx
Step 2: Rearrange the terms.
limx→021⋅xsinx
Step 3: Apply the special limit limx→0xsinx=1.
21⋅1=21
The limit is 21.
Second :
limx→0x1−cosx
Step 1: Substitute x=0 into the expression.
01−cos0=01−1=00
This is an indeterminate form, so we can use L'Hôpital's Rule.
Step 2: Apply L'Hôpital's Rule.
limx→0dxd(x)dxd(1−cosx)=limx→01sinx
Step 3: Substitute x=0 into the simplified expression.
sin(0)=0
The limit is 0.
Drop the next question.
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ScanSolve AI Answer
Welcome back ThegirlGodishelping🥰💙🫠 — missed you this week. Here are the solutions to the limit problems. 1. We need to evaluate the limit: _x 3 (x^3 - 27)/(x^2 - 9) Step 1: Substitute x=3 into the expression. (3^3 - 27)/(3^2 - 9) = (27 - 27)/(9 - 9) = (0)/(0) This is an indeterminate form, so we need to simplify the expression. Step 2: Factor the numerator and the denominator. Use the difference of cubes formula a^3 - b^3 = (a-b)(a^2+ab+b^2) and the difference of squares formula a^2 - b^2 = (a-b)(a+b). x^3 - 27 = (x-3)(x^2 + 3x + 9) x^2 - 9 = (x-3)(x+3) Step 3: Rewrite the limit with the factored expressions and cancel out the common term (x-3). _x 3 ((x-3)(x^2 + 3x + 9))/((x-3)(x+3)) = _x 3 (x^2 + 3x + 9)/(x+3) Step 4: Substitute x=3 into the simplified expression. (3^2 + 3(3) + 9)/(3+3) = (9 + 9 + 9)/(6) = (27)/(6) Step 5: Simplify the fraction. (27)/(6) = (9)/(2) The limit is (9)/(2). 2. We need to evaluate the limit: _x 7 sqrt(x+2) - 3x-7 Step 1: Substitute x=7 into the expression. sqrt(7+2) - 37-7 = sqrt(9) - 30 = (3-3)/(0) = (0)/(0) This is an indeterminate form, so we need to simplify the expression. Step 2: Multiply the numerator and denominator by the conjugate of the numerator, which is sqrt(x+2) + 3. _x 7 sqrt(x+2) - 3x-7 × sqrt(x+2) + 3sqrt(x+2) + 3 Step 3: Simplify the numerator using the difference of squares formula (a-b)(a+b) = a^2 - b^2. (sqrt(x+2))^2 - 3^2 = (x+2) - 9 = x-7 Step 4: Rewrite the limit with the simplified numerator. _x 7 (x-7)/((x-7)(sqrt(x+2) + 3)) Step 5: Cancel out the common term (x-7). _x 7 (1)/(sqrt(x+2) + 3) Step 6: Substitute x=7 into the simplified expression. (1)/(sqrt(7+2) + 3) = (1)/(sqrt(9) + 3) = (1)/(3+3) = (1)/(6) The limit is (1)/(6). 3. We need to evaluate the limit: _x (4x^2 - 5x + 1)/(sqrt(9x^4 + 2x^2 - 6)) Step 1: Identify the highest power of x in the denominator. Inside the square root, the highest power is x^4, so sqrt(x^4) = x^2. Step 2: Divide every term in the numerator and the denominator by x^2. For terms inside the square root, divide by x^4. _x (4x^2)/(x^2) - (5x)/(x^2) + (1)/(x^2)sqrt((9x^4)/(x^4) + (2x^2)/(x^4) - (6)/(x^4)) Step 3: Simplify the terms. _x (4 - 5)/(x) + (1)/(x^2)sqrt(9 + (2)/(x^2) - (6)/(x^4)) Step 4: Apply the limit. As x , terms of the form (c)/(x^n) approach 0. (4 - 0 + 0)/(sqrt(9 + 0 - 0)) = (4)/(sqrt(9)) Step 5: Simplify the expression. (4)/(3) The limit is (4)/(3). 4. We need to evaluate the limit: _x 0 ((5x))/((3x)) Step 1: Rewrite (3x) in terms of (3x) and (3x). _x 0 ((5x))/((3x))(3x) = _x 0 ((5x) (3x))/((3x)) Step 2: Rearrange the terms to use the special limit _u 0 ( u)/(u) = 1. _x 0 ( ((5x))/(5x) · (3x)/((3x)) · (5x)/(3x) · (3x) ) Step 3: Simplify the expression and apply the limit properties. _x 0 ( ((5x))/(5x) ) · _x 0 ( (3x)/((3x)) ) · _x 0 ( (5)/(3) ) · _x 0 ( (3x) ) Step 4: Evaluate each limit. 1 · 1 · (5)/(3) · (0) = 1 · 1 · (5)/(3) · 1 = (5)/(3) The limit is (5)/(3). 5. There are two problems labeled '5'. I will solve both. First problem 5: _x 0 (1 - x)/(x^2) Step 1: This is a standard limit. We can use the identity 1 - x = 2 ^2((x)/(2)). _x 0 (2 ^2(x)/(2))x^2 Step 2: Rearrange the terms to use the special limit _u 0 ( u)/(u) = 1. _x 0 2 · ((x)/(2))x · ((x)/(2))x Step 3: Multiply and divide by (1)/(2) for each ((x)/(2))x term. _x 0 2 · ((x)/(2))(x)/(2) · 2 · ((x)/(2))(x)/(2) · 2 Step 4: Simplify and apply the limit. _x 0 2 · (1)/(2) · (1)/(2) · ( ((x)/(2))(x)/(2) ) · ( ((x)/(2))(x)/(2) ) = 2 · (1)/(4) · 1 · 1 = (1)/(2) Alternatively, using L'Hôpital's Rule (since substituting x=0 gives (0)/(0)): Step 1: Apply L'Hôpital's Rule. _x 0 (d)/(dx)(1 - x)(d)/(dx)(x^2) = _x 0 ( x)/(2x) Step 2: Rearrange the terms. _x 0 (1)/(2) · ( x)/(x) Step 3: Apply the special limit _x 0 ( x)/(x) = 1. (1)/(2) · 1 = (1)/(2) The limit is (1)/(2). Second problem 5: _x 0 (1 - x)/(x) Step 1: Substitute x=0 into the expression. (1 - 0)/(0) = (1 - 1)/(0) = (0)/(0) This is an indeterminate form, so we can use L'Hôpital's Rule. Step 2: Apply L'Hôpital's Rule. _x 0 (d)/(dx)(1 - x)(d)/(dx)(x) = _x 0 ( x)/(1) Step 3: Substitute x=0 into the simplified expression. (0) = 0 The limit is 0. Drop the next question.