AlgebraEasy–MediumLine through the origin with slope −1
Algebra practice question
Which equation represents a line in the xy-plane that has a slope of −1 and passes through the origin?
- A. y = −xCorrect
- B. y = x − 1
- C. y = −1
- D. x = −1
Answer: A. y = −x
Slope −1 with y-intercept 0 gives y = −1 · x + 0 = −x. Check: (0, 0) satisfies it.
Why the other answers are wrong
- B. y = x − 1
- y = x − 1 has slope +1 and doesn't pass through the origin.
- C. y = −1
- y = −1 is a horizontal line with slope 0.
- D. x = −1
- x = −1 is a vertical line and doesn't pass through the origin.
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