Solve the Rational Equation: 7/(x-5) = 15/(3-x)

Question

Solve for X:

7x5=153x \frac{7}{x-5}=\frac{15}{3-x}

Video Solution

Solution Steps

00:00 Find X
00:04 Multiply by the common denominator to eliminate fractions
00:28 Simplify as much as possible
00:39 Carefully open parentheses properly, multiply by each factor:
00:56 Arrange the equation so that one side contains only the unknown X
01:15 Collect like terms
01:26 Isolate X
01:44 And this is the solution to the problem

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Transform the equation to ensure the denominators are handled correctly.
  • Step 2: Apply cross-multiplication to eliminate the fractions.
  • Step 3: Simplify the resulting equation and solve for xx.
  • Step 4: Verify that the solution does not make either denominator zero.

Now, let's work through each step:

Step 1: Recognize that 3x=(x3)3-x = -(x-3), so we can rewrite the equation as:

7x5=15(x3)\frac{7}{x-5}=\frac{15}{-(x-3)}, which simplifies to 7x5=15x3\frac{7}{x-5} = -\frac{15}{x-3}.

Step 2: Apply cross-multiplication:

Multiply both sides to clear the fractions:

7(x3)=15(x5)7 \cdot (x-3) = -15 \cdot (x-5).

Step 3: Distribute and solve for xx:

Expanding both sides, we get: 7x21=15x+757x - 21 = -15x + 75.

Bring all terms involving xx to one side:

7x+15x=75+217x + 15x = 75 + 21.

This simplifies to:

22x=9622x = 96.

Now, solve for xx:

x=9622x = \frac{96}{22}.

Simplify the fraction:

x=4811x = \frac{48}{11}.

Convert to a decimal, if preferred:

x4.36x \approx 4.36.

Step 4: Verify that the solution does not make either denominator zero:

With x=4.36x = 4.36, neither x5x - 5 nor 3x3 - x is zero, so the solution is valid.

Therefore, the solution to the equation is 4.36\boxed{4.36}.

Answer

4.36 4.36