About Chanda Walker Expertise Any high school level math questions. Please don't just type the math problem without any comments. If you don't tell me what your trouble is, I can't help.
Experience Years of tutoring, BS in mathematics, constant use of mathematics in career.
Question Find the equation of the line that is perpendicular to 2y + x = 8 and that passes through the point (-2,-1)
Please answer asap have a test tomorow.
Answer To find the equation of a line that perpendicular to another we have 3 steps.
1) get the original equation into the "slope-intercept form"
2) locate the slope and convert it to a perpendicular slope
3) use that new slope and the point given to find final equation
I'll demonstrate.
The original equation can be written like this with some manipulation of terms:
y = -1/2 x + 4
That is in the slope intercept form (y = mx + b). Can you see that m = (-1/2) and b = 4. This is a critical step. (m is the slope, b is the intercept.)
Next, we need to grab that slope and convert it to a perpendicular slope now. The way to do that is to invert it and multiply by -1.
So here is the equation; it looks worse than it is.
-1/m = -1/(-1/2) = 2
Ok, the slope of our new line is 2. Let's see what our equation looks like thus far . . .
y = 2x + b
DON'T use the b from above. We need to find a new b for our new line. To do that, we use the point given. Substitute the point given in for the y and x and solve for b.
(-1) = 2*(-2) + b
-1 = -4 + b
b = 3
Now we are done. Just stick that into our equation and bingo.
y = 2x + 3
Hope this helps. Please let me know if you have further questions.
