Solve the Rational Equation: (x³+1)/(x-1)² = x+4

Question

Solve the following equation:

x3+1(x1)2=x+4 \frac{x^3+1}{(x-1)^2}=x+4

Video Solution

Solution Steps

00:00 Solve
00:08 Multiply to eliminate the fraction
00:24 Use the distributive property of multiplication to expand the parentheses
00:47 Calculate the multiplication
00:55 Make sure to properly open parentheses
01:04 Each term in the first parentheses multiplies each term in the second parentheses
01:25 Reduce where possible
01:32 Collect like terms
01:42 Arrange the equation so that one side equals 0
01:50 Use the quadratic formula to find possible solutions
02:05 Calculate the multiplication
02:20 Solve for the positive option
02:26 This is one solution
02:29 Now solve for the negative option
02:33 This is the second solution
02:37 Note the domain restrictions, the denominator must not equal 0
02:47 And this is the solution to the problem

Step-by-Step Solution

To solve this equation, we follow these steps:

  • Step 1: Multiply both sides by (x1)2(x-1)^2 to eliminate the fraction.
  • Step 2: Expand and simplify both sides of the equation.
  • Step 3: Rearrange the equation to form a polynomial equal to zero.
  • Step 4: Solve the resulting polynomial using factorization or the quadratic formula.

Now, let's execute these steps:

Step 1: Multiply both sides by (x1)2(x-1)^2:
(x3+1)=(x+4)(x1)2(x^3 + 1) = (x + 4)(x - 1)^2

Step 2: Expand the right side:
(x+4)(x22x+1)=x(x22x+1)+4(x22x+1) (x + 4)(x^2 - 2x + 1) = x(x^2 - 2x + 1) + 4(x^2 - 2x + 1)

Calculating each part yields:
x(x22x+1)=x32x2+x x(x^2 - 2x + 1) = x^3 - 2x^2 + x
4(x22x+1)=4x28x+4 4(x^2 - 2x + 1) = 4x^2 - 8x + 4

Add these together:
x32x2+x+4x28x+4=x3+2x27x+4 x^3 - 2x^2 + x + 4x^2 - 8x + 4 = x^3 + 2x^2 - 7x + 4

Step 3: Combine terms and rearrange:
x3+1=x3+2x27x+4 x^3 + 1 = x^3 + 2x^2 - 7x + 4

Simplify by cancelling x3x^3 from both sides:
1=2x27x+4 1 = 2x^2 - 7x + 4

Move 1 to the right side:
0=2x27x+3 0 = 2x^2 - 7x + 3

Step 4: Solve the quadratic equation 2x27x+3=0 2x^2 - 7x + 3 = 0 .

Using the quadratic formula, x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} , where a=2 a = 2 , b=7 b = -7 , and c=3 c = 3 .

Calculate the discriminant:
b24ac=(7)2423=4924=25 b^2 - 4ac = (-7)^2 - 4 \cdot 2 \cdot 3 = 49 - 24 = 25

Now plug into the quadratic formula:
x=7±254 x = \frac{7 \pm \sqrt{25}}{4}

Simplify:
x=7±54 x = \frac{7 \pm 5}{4}

Two solutions arise:
x=124=3 x = \frac{12}{4} = 3 and x=24=12 x = \frac{2}{4} = \frac{1}{2}

Since x=1 x = 1 would make the denominator zero, it is not a valid solution for the original equation.

Therefore, the solution to the problem is x=3 x = 3 or x=12 x = \frac{1}{2} .

Answer

x=3,12 x=3,\frac{1}{2}