Question

Y=-1/2x +7

Line k is perpendicular to the line defined by the equation
above and passes through the point (4,0). Which of the
following points also lies on line k?
A) (0,8)
B) (2,-4)

C) (2,-2)
D) (2,8)

Answer 1

B; (2,-4)

Explanation:

The general equation of a straight line is;

y = mx + b

where m is the slope and b is the y-intercept

So from the question, when we look at the given equation, its slope is -1/2

mathematically, when two lines are perpendicular, the product of their slopes is -1

thus;

m1 * m2 = -1

m2 * -1/2 = -1

-m2 = -2

m2 = 2

The general equation form is;

y-y1 = m(x-x1)

where (x1,y1) = (4,0)

y-0 = 2(x-4)

y = 2x - 8

So, now we look at the point that will work for this equation

For the line that will work, if we substitute its x-value, we get the y-value

Let us take a look at option B

y = 2(2) -8 = 4-8 = -4

we can see that (2,-4) works