Solve the Complex Fraction Equation: -7/((x+4)×3-7) = 2/(5+x)

Question

Solve for X:

7(x+4)×37=25+x \frac{-7}{(x+4)\times3-7}=\frac{2}{5+x}

Video Solution

Solution Steps

00:00 Find X
00:04 Multiply by denominators to eliminate fractions
00:42 Carefully open parentheses properly, multiply by each term
01:08 Collect like terms
01:17 Carefully open parentheses properly, multiply by each term
01:27 Arrange the equation so that X is isolated on one side
01:47 Collect like terms
01:54 Isolate X
02:10 And this is the solution to the problem

Step-by-Step Solution

To solve the given equation, we'll use the approach of cross-multiplication. Let's work through it step by step:

  • Step 1: Simplify the denominators:
    • In (x+4)×37(x+4)\times3-7, first compute the multiplication: (x+4)×3=3x+12(x+4)\times3 = 3x + 12.
    • Subtract 7, obtaining: 3x+127=3x+53x + 12 - 7 = 3x + 5.
  • Step 2: Plug these simplifications back into the equation:
  • 73x+5=25+x\frac{-7}{3x+5} = \frac{2}{5+x}

  • Step 3: Cross-multiply to clear the fractions:
  • 7(5+x)=2(3x+5)-7(5+x) = 2(3x+5)

  • Step 4: Expand both sides:
    • 7×5=35-7 \times 5 = -35 and 7×x=7x-7 \times x = -7x, so the left side is 357x-35 - 7x.
    • For the right side: 2×3x=6x2 \times 3x = 6x and 2×5=102 \times 5 = 10, so it equals 6x+106x + 10.
  • Step 5: Set up the equation from expansions:
  • 357x=6x+10-35 - 7x = 6x + 10

  • Step 6: Solve for x x :
    • Add 7x 7x to both sides to collect x x terms on one side:
    • 35=6x+10+7x-35 = 6x + 10 + 7x

    • This simplifies to: 35=13x+10-35 = 13x + 10.
    • Subtract 10 from both sides:
    • 3510=13x-35 - 10 = 13x

      45=13x-45 = 13x

    • Divide both sides by 13 to solve for x x :
    • x=4513x = \frac{-45}{13}

    • Convert 4513-\frac{45}{13} to a decimal: 3.46-3.46 (rounded to two decimal places).
  • Step 7: Verify:
    • Verify 5+x0 5 + x \neq 0 and 3x+50 3x + 5 \neq 0 based on our found value, ensuring no division by zero. Both conditions are true.

Therefore, the solution to the problem is x=3.46 x = -3.46 .

Answer

3.46 -3.46