Find the value of the following limits: 5. lim (x->2) [1/(x(x-2)2) - 1/(x2-3x+2)]; 6. lim (x->1) [1/(1-x) - 3/(1-x3)]
|Mathematics
Find the value of the following limits: 5. lim (x->2) [1/(x(x-2)2) - 1/(x2-3x+2)]; 6. lim (x->1) [1/(1-x) - 3/(1-x3)]
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3 steps
Answer
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Here are the solutions to the limit problems.
We need to find the value of:
limx→2[x(x−2)21−x2−3x+21]
Step 1: Factor the denominator of the second term.
The quadratic x2−3x+2 factors as (x−1)(x−2).
The expression becomes:
limx→2[x(x−2)21−(x−1)(x−2)1]
Step 2: Combine the fractions using a common denominator.
The common denominator is x(x−1)(x−2)2.
=limx→2[x(x−1)(x−2)2(x−1)−x(x−1)(x−2)2x(x−2)]=limx→2x(x−1)(x−2)2(x−1)−x(x−2)
Step 3: Simplify the numerator.
=limx→2x(x−1)(x−2)2x−1−x2+2x=limx→2x(x−1)(x−2)2−x2+3x−1
Step 4: Evaluate the limit.
Substitute x=2 into the numerator: −(2)2+3(2)−1=−4+6−1=1.
Substitute x=2 into the denominator: 2(2−1)(2−2)2=2(1)(0)2=0.
Since the numerator approaches 1 and the denominator approaches 0 from the positive side (because (x−2)2 is always positive, and x(x−1) is positive near x=2), the limit is 0+1.
The value of the limit is ∞.
We need to find the value of:
limx→1(1−x1−1−x33)
Step 1: Factor the denominator of the second term.
The difference of cubes formula is a3−b3=(a−b)(a2+ab+b2). So, 1−x3=(1−x)(1+x+x2).
The expression becomes:
limx→1(1−x1−(1−x)(1+x+x2)3)
Step 2: Combine the fractions using a common denominator.
The common denominator is (1−x)(1+x+x2).
=limx→1(1−x)(1+x+x2)(1+x+x2)−3
Step 3: Simplify the numerator.
=limx→1(1−x)(1+x+x2)x2+x−2
Step 4: Factor the numerator and simplify.
The numerator x2+x−2 factors as (x+2)(x−1).
Also, note that (1−x)=−(x−1).
=limx→1−(x−1)(1+x+x2)(x+2)(x−1)
Cancel out the common factor (x−1) (since x=1 as x→1):
=limx→1−(1+x+x2)x+2
Step 5: Evaluate the limit by substituting x=1.
=−(1+1+12)1+2=−(1+1+1)3=−33=−1
The value of the limit is −1.
We need to find the value of:
limx→2x2+32x−8x4−4
Step 1: Check for indeterminate form.
Substitute x=2 into the numerator: (2)4−4=4−4=0.
Substitute x=2 into the denominator: (2)2+32(2)−8=2+3(2)−8=2+6−8=0.
This is an indeterminate form 00, so we need to factor.
Step 2: Factor the numerator.
The numerator is a difference of squares: x4−4=(x2)2−22=(x2−2)(x2+2).
Further factor x2−2=(x−2)(x+2).
So, x4−4=(x−2)(x+2)(x2+2).
Step 3: Factor the denominator.
Since substituting x=2 into the denominator yields 0, (x−2) must be a factor.
We can find the other factor by polynomial division or by inspection:
x2+32x−8=(x−2)(x+42).
Step 4: Substitute the factored forms into the limit expression.
=limx→2(x−2)(x+42)(x−2)(x+2)(x2+2)
Step 5: Cancel the common factor and evaluate the limit.
Cancel out (x−2) (since x=2 as x→2):
=limx→2x+42(x+2)(x2+2)
Now substitute x=2:
=2+42(2+2)((2)2+2)=52(22)(2+2)=52(22)(4)=5282=58
The value of the limit is 58.
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This mathematics problem involves applying core mathematical principles and formulas. Below you will find a complete step-by-step solution with detailed explanations for each step, helping you understand not just the answer but the method behind it.
ScanSolve AI Answer
Here are the solutions to the limit problems. 5. We need to find the value of: _x 2 [ (1)/(x(x-2)^2) - (1)/(x^2-3x+2) ] Step 1: Factor the denominator of the second term. The quadratic x^2-3x+2 factors as (x-1)(x-2). The expression becomes: _x 2 [ (1)/(x(x-2)^2) - (1)/((x-1)(x-2)) ] Step 2: Combine the fractions using a common denominator. The common denominator is x(x-1)(x-2)^2. = _x 2 [ ((x-1))/(x(x-1)(x-2)^2) - (x(x-2))/(x(x-1)(x-2)^2) ] = _x 2 ((x-1) - x(x-2))/(x(x-1)(x-2)^2) Step 3: Simplify the numerator. = _x 2 (x-1 - x^2 + 2x)/(x(x-1)(x-2)^2) = _x 2 (-x^2 + 3x - 1)/(x(x-1)(x-2)^2) Step 4: Evaluate the limit. Substitute x=2 into the numerator: -(2)^2 + 3(2) - 1 = -4 + 6 - 1 = 1. Substitute x=2 into the denominator: 2(2-1)(2-2)^2 = 2(1)(0)^2 = 0. Since the numerator approaches 1 and the denominator approaches 0 from the positive side (because (x-2)^2 is always positive, and x(x-1) is positive near x=2), the limit is (1)/(0^+). The value of the limit is . 6. We need to find the value of: _x 1 ( (1)/(1-x) - (3)/(1-x^3) ) Step 1: Factor the denominator of the second term. The difference of cubes formula is a^3-b^3 = (a-b)(a^2+ab+b^2). So, 1-x^3 = (1-x)(1+x+x^2). The expression becomes: _x 1 ( (1)/(1-x) - (3)/((1-x)(1+x+x^2)) ) Step 2: Combine the fractions using a common denominator. The common denominator is (1-x)(1+x+x^2). = _x 1 ((1+x+x^2) - 3)/((1-x)(1+x+x^2)) Step 3: Simplify the numerator. = _x 1 (x^2 + x - 2)/((1-x)(1+x+x^2)) Step 4: Factor the numerator and simplify. The numerator x^2+x-2 factors as (x+2)(x-1). Also, note that (1-x) = -(x-1). = _x 1 ((x+2)(x-1))/(-(x-1)(1+x+x^2)) Cancel out the common factor (x-1) (since x 1 as x 1): = _x 1 (x+2)/(-(1+x+x^2)) Step 5: Evaluate the limit by substituting x=1. = (1+2)/(-(1+1+1^2)) = (3)/(-(1+1+1)) = (3)/(-3) = -1 The value of the limit is -1. 7. We need to find the value of: _x sqrt(2) (x^4 - 4)/(x^2 + 3sqrt(2)x - 8) Step 1: Check for indeterminate form. Substitute x=sqrt(2) into the numerator: (sqrt(2))^4 - 4 = 4 - 4 = 0. Substitute x=sqrt(2) into the denominator: (sqrt(2))^2 + 3sqrt(2)(sqrt(2)) - 8 = 2 + 3(2) - 8 = 2 + 6 - 8 = 0. This is an indeterminate form (0)/(0), so we need to factor. Step 2: Factor the numerator. The numerator is a difference of squares: x^4 - 4 = (x^2)^2 - 2^2 = (x^2 - 2)(x^2 + 2). Further factor x^2 - 2 = (x - sqrt(2))(x + sqrt(2)). So, x^4 - 4 = (x - sqrt(2))(x + sqrt(2))(x^2 + 2). Step 3: Factor the denominator. Since substituting x=sqrt(2) into the denominator yields 0, (x-sqrt(2)) must be a factor. We can find the other factor by polynomial division or by inspection: x^2 + 3sqrt(2)x - 8 = (x - sqrt(2))(x + 4sqrt(2)). Step 4: Substitute the factored forms into the limit expression. = _x sqrt(2) (x - sqrt(2))(x + sqrt(2))(x^2 + 2)(x - sqrt(2))(x + 4sqrt(2)) Step 5: Cancel the common factor and evaluate the limit. Cancel out (x - sqrt(2)) (since x sqrt(2) as x sqrt(2)): = _x sqrt(2) (x + sqrt(2))(x^2 + 2)x + 4sqrt(2) Now substitute x=sqrt(2): = (sqrt(2) + sqrt(2))((sqrt(2))^2 + 2)sqrt(2) + 4sqrt(2) = (2sqrt(2))(2 + 2)5sqrt(2) = (2sqrt(2))(4)5sqrt(2) = 8sqrt(2)5sqrt(2) = (8)/(5) The value of the limit is (8)/(5). Last free one today — make it count tomorrow, or type /upgrade for unlimited.