Question

Difficulty: MediumLinear Equations in One Variable
If xx satisfies the linear equation
3(x4)42x+16=x+235\frac{3(x - 4)}{4} - \frac{2x + 1}{6} = \frac{x + 2}{3} - 5
what is the value of 2x+52x + 5?
  1. A
    31-31
  2. 23-23Answer
  3. C
    14-14
  4. D
    4141
  5. E
    8787

Answer

The value of 2x+52x + 5 is 23-23.
Clearing denominators by multiplying the entire equation by 1212 gives 9(x4)2(2x+1)=4(x+2)609(x - 4) - 2(2x + 1) = 4(x + 2) - 60. Expanding both sides yields 9x364x2=4x+8609x - 36 - 4x - 2 = 4x + 8 - 60, which simplifies to 5x38=4x525x - 38 = 4x - 52. Isolating xx gives x=14x = -14. Substituting x=14x = -14 into the target expression 2x+52x + 5 yields 2(14)+5=232(-14) + 5 = -23.

Step-by-Step Solution

1
Clear the denominators by multiplying every term on both sides of the equation by the least common multiple of 4,6,4, 6, and 33, which is 1212.
123(x4)4122x+16=12x+2312512 \cdot \frac{3(x - 4)}{4} - 12 \cdot \frac{2x + 1}{6} = 12 \cdot \frac{x + 2}{3} - 12 \cdot 5, leading to 9(x4)2(2x+1)=4(x+2)609(x - 4) - 2(2x + 1) = 4(x + 2) - 60.
Clearing denominators simplifies the multi-step fractional equation into an integer linear equation.
2
Expand all grouping symbols and combine like terms on both sides.
9x364x2=4x+8609x - 36 - 4x - 2 = 4x + 8 - 60, which simplifies to 5x38=4x525x - 38 = 4x - 52.
Distributing terms carefully ensures proper sign distribution, especially for negative signs across parentheses.
3
Isolate the variable xx on one side of the equation.
5x4x=52+385x - 4x = -52 + 38, giving x=14x = -14.
Subtracting 4x4x and adding 3838 isolates xx.
4
Evaluate the target expression 2x+52x + 5 using the solved value x=14x = -14.
2(14)+5=28+5=232(-14) + 5 = -28 + 5 = -23.
The question asks for the value of 2x+52x + 5, not xx.

Key Concept

Solving linear equations in one variable with fractional coefficients and evaluating algebraic expressions
Estimated Time:1m 30s
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