Math Is Fun Forum

icy_A

Member

Registered: 2007-10-04

Posts: 5

Writing Linear Equations(i Need Help)

Write An Equation In Slope Intercept Form For The Line That Satifies Each Setof Conditions.

Slope 0, Passes Through (0,-10)

How Do You Do This Problem???

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: Writing Linear Equations(i Need Help)

If a line has slope = 0, then it is a horizontal line. If you think about it graphically it means that the line stays at the same y-coordinate, it only changes its x-coordinate.

Therefore the equation is simply

.

There is no x in the equation because no matter what x is, y will always be -10.

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Writing Linear Equations(i Need Help)

I also prefer this equation:  y - yPointKnow = slope(x - xPointKnown), where a known coordinate is (xPointKnown, yPointKnown).
Because it works for any point anywhere except at infinities I guess.
The equation they are referring to is y = (slope)(x) + yInterceptWhenXisZero.
For slope zero and (0, -10), just plug them in.
y = 0x + (-10)
y = 0x - 10
y = -10     is true too, but they might want you to
just stop in the form of y = mx + b,
so just write y = 0x - 10 and state that it can be further simplified.

If we use my favorite equation instead, then
it goes like this:
y - (-10) = 0(x - 0)
y + 10 = 0(x - 0)
y = 0(x - 0) - 10
y = 0x - 0 - 10
y = 0x - 10  (This is in the form y = mx + b, or y-intercept form)
y = - 10

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