Intercepts of a straight line: For the line through points (−2, 8) and (5, 7), determine which axes it cuts.

Difficulty: Easy

Correct Answer: cuts both the axes

Explanation:


Introduction / Context:
Given two points, we can write the equation of the line and test intercepts by checking where it meets the x- and y-axes. This reinforces slope-intercept concepts and evaluating linear equations at y = 0 or x = 0.



Given Data / Assumptions:

  • Points: A(−2, 8) and B(5, 7).
  • We want to know whether the line meets the x-axis, the y-axis, both, or neither.


Concept / Approach:
Compute slope m = (y2 − y1)/(x2 − x1). Use point-slope form to obtain the equation. Then find the y-intercept by setting x = 0, and the x-intercept by setting y = 0.



Step-by-Step Solution:

Slope m = (7 − 8)/(5 − (−2)) = −1/7Equation via point (−2, 8): y − 8 = (−1/7)(x + 2)For y-intercept (x = 0): y − 8 = (−1/7)(0 + 2) = −2/7 ⇒ y = 8 − 2/7 = 54/7 (exists)For x-intercept (y = 0): 0 − 8 = (−1/7)(x + 2) ⇒ −8 = −(x + 2)/7 ⇒ 56 = x + 2 ⇒ x = 54 (exists)


Verification / Alternative check:
Because the slope is finite and not zero, and the line's equation yields finite intercepts at both substitutions, the line crosses both axes exactly once.



Why Other Options Are Wrong:
It is not parallel to either axis (slope is −1/7), so it cannot avoid both axes nor cut only one axis.



Common Pitfalls:
Sign mistakes when applying point-slope form or solving for intercepts can lead to wrong conclusions about which axes are cut.



Final Answer:
cuts both the axes

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