Question

Difficulty: MediumReal Numbers, Number Line, and Absolute Value

On the real number line, xx is a negative real number such that ∣5−2x∣=11|5 - 2x| = 11, and yy is a positive real number such that ∣3y+1∣=13|3y + 1| = 13. What is the distance on the real number line between xx and yy?

Answer: 7

Answer

The distance between xx and yy on the real number line is 7.
Solving ∣5−2x∣=11|5 - 2x| = 11 with x<0x < 0 yields x=−3x = -3. Solving ∣3y+1∣=13|3y + 1| = 13 with y>0y > 0 yields y=4y = 4. The distance between −3-3 and 44 on the number line is ∣4−(−3)∣=7|4 - (-3)| = 7.

Step-by-Step Solution

1
Solve for the negative real number xx using the equation ∣5−2x∣=11|5 - 2x| = 11.
x=−3x = -3
The equation splits into 5−2x=115 - 2x = 11 (yielding x=−3x = -3) and 5−2x=−115 - 2x = -11 (yielding x=8x = 8). Since xx must be negative, x=−3x = -3 is selected.
2
Solve for the positive real number yy using the equation ∣3y+1∣=13|3y + 1| = 13.
y=4y = 4
The equation splits into 3y+1=133y + 1 = 13 (yielding y=4y = 4) and 3y+1=−133y + 1 = -13 (yielding y=−143y = -\frac{14}{3}). Since yy must be positive, y=4y = 4 is selected.
3
Compute the distance between xx and yy on the number line.
7
The distance between two points on the number line is given by ∣y−x∣=∣4−(−3)∣=7|y - x| = |4 - (-3)| = 7.

Key Concept

Distance on the real number line between two points aa and bb is given by ∣a−b∣|a - b|, solved by evaluating absolute value equations under given sign constraints.

Alternative Method

Plot the candidate solutions for xx (x=−3x = -3 and x=8x = 8) and yy (y=4y = 4 and y=−14/3y = -14/3) on a number line, then directly count units between the valid points x=−3x = -3 and y=4y = 4.
Estimated Time:1m 15s
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