Find an equation of the line described. Leave the solution in the form Ax + By = C. The line has slope m = − 4/5 and contains (0, 8).

Question

Find an equation of the line described. Leave the solution in the form Ax + By = C.

The line has slope m = − 4/5

and contains (0, 8).

Can Someone just help me get the answer for this one, I have others that are similar but I just need one as an example to help me finish the others.

Answer 1

Hello, Alyssa,

For my own benefit, I'm changing the format of the equation and then moving back to the form specified. The standard equation for a straight line is y = mx + B, where m is the slope and b is the y intercept (the value of y when x=0).

We are gien the slope, so:

y = (-4/5)x + b

We also know of one point (0,8) that satisfies this equation (is on the line), so use that to calculate b.

y = (-4/5)x + b

8 = (-4/5)*0 + b

b = 8

So the equation is y = (-4/5)x + b

Put it in the requested format:

Ax + By = C

(-4/5)x - y = -b

or (4/5)x + y = b

Bob

Answer 2

y= -4x/5 + b

8 = b

y=-4x/5 + 8 is the equation of a line with slope =-4/5 that goes through (0,8)

8 or (0,8) is the y intercept, the coefficient of the x term is the slope, when the equation is solved for y

multiply by 5 to get

5y =-4x + 40

4x+5y = 40 where Ax+By=C and A=4, B=5, C=40