Question

Difficulty: EasyLinear Equations in One Variable
If xx satisfies the linear equation 4(x2)15=2x+34(x - 2) - 15 = 2x + 3 which of the following statements must be true? Select all that apply.
  1. xx is a prime numberAnswer
  2. 2x52x - 5 is equal to 2121Answer
  3. x+7x + 7 is a multiple of 55Answer
  4. D
    xx is an even integer
  5. E
    x+12=6\frac{x + 1}{2} = 6

Answer

The correct statements are that xx is a prime number, 2x52x - 5 is equal to 2121, and x+7x + 7 is a multiple of 55.
Solving the equation 4(x2)15=2x+34(x - 2) - 15 = 2x + 3 yields x=13x = 13. Evaluating the choices with x=13x = 13 confirms that 1313 is a prime number, 2(13)5=212(13) - 5 = 21, and 13+7=2013 + 7 = 20 (a multiple of 55).

Step-by-Step Solution

1
Expand the left side of the linear equation by distributing the constant term.
4x815=2x+34x - 8 - 15 = 2x + 3
Distribution removes parentheses so like terms can be combined.
2
Combine constant terms on the left side of the equation.
4x23=2x+34x - 23 = 2x + 3
Simplifying 815-8 - 15 yields 23-23.
3
Isolate variable terms on the left side and constant terms on the right side by subtracting 2x2x and adding 2323 to both sides.
2x=262x = 26
Subtracting 2x2x gives 2x2x on the left, and adding 2323 gives 2626 on the right.
4
Divide both sides of the equation by 22 to solve for xx.
x=13x = 13
Dividing 2626 by 22 determines the unique value of xx.
5
Test each statement using x=13x = 13.
1313 is prime (True); 2(13)5=212(13) - 5 = 21 (True); 13+7=2013 + 7 = 20 which is a multiple of 55 (True); 1313 is even (False); 13+12=76\frac{13 + 1}{2} = 7 \neq 6 (False).
Direct evaluation identifies which statements hold true.

Key Concept

Solving linear equations in one variable and evaluating numerical properties of the solution.
Estimated Time:1m 0s
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