OG详解-OG9 数学2 Q8

Choice D is correct. A linear relationship can be represented by an equation of the form y = mx+b, where m and b are constants. It’s given in the table that when x = 0, y = 18. Substituting 0 for x and 18 for y in y = mx+b yields 18 = m(0)+b, or 18 = b. Substituting 18 for b in the equation y = mx+b yields y = mx+18. It’s also given in the table that when x = 1, y = 13. Substituting 1 for  x and 13 for y in the equation y = mx+18 yields 13 = m(1)+18, or 13 = m+18. Subtracting 18 from both sides of this equation yields -5 = m. Therefore, the equation y = -5x+ 18 represents the relationship between x and y.

Choice A is incorrect and may result from conceptual or calculation errors. Choice B is incorrect and may result from conceptual or calculation errors. Choice C is incorrect and may result from conceptual or calculation errors.