Check the coordinates of the given points in each of the given possible answer functions (2, –21) and (5, –45), until you find the function satisfied by these two points.
Do these points satisfy the equation y = –8x – 5? Substitute 2 for x and -21 for y and determine whether or not the resulting equation is true:
-21 = -(2) - 5 This is false, and we can state that confidentally even
without checking whether the other given point is a solution.
Moving on to the next equation y = –8x + 5:
Is -21 = -8(2) + 5? Is -21 = -16 + 5? Is -21 = -11? No. Move on to the next equation: y = 8x – 5. Is -21 = 8(2) -5 true? No. Move on to the next equation:
y = 8x+ 5 Is -21 = 8(2) + 5? No.
It appears that the given points (2,-21) and (-5,-45) are not solutions of any of the four given equations.
