The equation of the line passing through the pair of points
(0,-2) and (2,5) is:

c. y = 3x - 2

Nope, Let's try this by hand and then by calculator. First, by hand, we find the slope by using this formula: (y2 - y1)/(x2 - x1). In our case we have [5 - (-2)]/(2 - 0) = 7/2 = 3.5. So, we need a linear equation which has a slope of 3.5, but the equation in choice c only has a slope of 3. Now lets try this using our calculator:

  • Turn on your calculator.
  • Put your calculator in LR mode. Mode 3 for an S type calculator or Mode 2 for a D or H model.
  • Press shift AC
  • Press 0 then the XoYo button (it's the key directly above the 8 and 9 keys).
  • Press 2 then the change sign button [(+/-) directly above the 7 key] then press the M+ button.
  • Press 2 then the XoYo button.
  • Press 5 then the M+ button.
  • Press Shift 7 to find the y-intercept (a) of the linear equation.
  • Press Shift 8 to find the slope (b) of the linear equation.
  • The equation for the line that passes through these two slopes is y = a + bx, where you replace a and b with the values you just got.

 

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