Question

A line passes through the point (4, –2) and has a slope of 1/2. What is the value of a if the point (–4, a) is also on the line?

Answer 1

y = mx + b
slope(m) = 1/2
(4,-2)...x = 4 and y = -2
sub and find b, the y int
-2 = 1/2(4) + b
-2 = 2 + b
-2 - 2 = b
-4 = b

the equation of the line is : y = 1/2x - 4

y = 1/2x - 4.......(-4,a)...when x = -4
y = 1/2(-4) - 4
y = -2 - 4
y = -6 .......so the value of a = - 6

Answer 2

  Use the formula of the slope.
M = y2 - y1 / x2 - x1

Then solve for a

   1/2 = a-(-2) / -4-4
      1/2 = a + 2 / -8
-8(1/2) = a + 2
        -4 = a + 2
        -6 = a

Therefore, A is -6