Hello, Paola,
The standard form for an equation of a straight line is y = mx + b, where m is the slope and b the y-intercept (the value of y when x = 0). From the two points we can calculate the slope, m. M is the change in y per change in x. The change in y for these two points, (-5,8) and (5,0), is -8, The change in x is (5 -(-5)) or 10. Slope is therefore (-8/10), or -0.8.
That gives us y = -0.8x + b
To find b, use either of the two points and solve for b:
E.g., 8 = (-0.8(-5)) + b
8 = 4 + b
b = 4
The equation becomes y = -0.8x + b
Bob
