Question

Write the equation of the line that contains the point (−2, -9) and is 4) Parallel to y = 8x + 7 5) Perpendicular to y = 8x + 7

Answer 1

Answer:

a. y = 8x + 7

b. 8y = -x-74

Step-by-step explanation:

Here, we want to write the equation of a line which is parallel to y = 8x + 7 and passes through the given point

Since the line we want to write the equation is parallel to y = 8x + 7, it means that they have the same slope

Mathematically we can write the equation of a line as y = mx + c where m is the slope. Comparing this with y = 8x + 7, our slope is therefore 8

Now, the slope of our new line is also 8

We now make use of the point slope method to write the equation

Mathematically the point slope method is;

y-y1 = m(x-x1)

where our (x1,y1) = (-2,-9)

y-(-9) = 8(x -(-2))

y + 9 = 8(x + 2)

y + 9 = 8x + 16

y = 8x + 16-9

y = 8x + 7

For the second line, it is perpendicular to y = 8x + 7

Here too, we have the slope as 8

Now since they are perpendicular, it means that the product of the slopes is equal to -1

m1 * m2 = -1

8 * m2 = -1

m2 = -1/8

Now;

y-y1 = m(x-x1)

our point still remains same (-2,-9)

y-(-9) = -1/8 (x -(-2))

y + 9 = -1/8(x + 2)

8(y + 9) = -1(x + 2)

8y + 72 = -x -2

8y = -x -2-72

8y = -x-74