perpendicular to the graph of 3x-4y=5?
a. -3x - 4y = -5
b. 16x + 12y = -15
c. 3x + 4y = 5
d. 4x - 3y = 6
The teacher already said it was B, but I don't know how to get that. Do I put it in slope-intercept form first?
2007-06-04 16:21:47 · 8 answers · asked by H. 2 in Science & Mathematics ➔ Mathematics
Slopes of equations written in this form, Ax +By=C, have the formula -A/B. That makes a. 3/4; b. -4/3;c. -3/4; d. 4/3. The original equation has a slope of 3/4 so a perepndicular would have a slope of -4/3 so b. is the correct answer.
2007-06-04 16:30:38 · answer #1 · answered by MollyMAM 6 · 0⤊ 0⤋
The line we have is
3x - 4y = 5
or 4y = 3x - 5
y = 3/4 * x - 5/4
The slope is 3/4
A perpendicular line must have slope -4/3 since hte produce of the slope of perpendicular lines = -1.
So out of all your choices, B is the onlyl one that has a slope of -4/3
16x + 12y = -15
12y = -16x - 15
y = -4/3 * x - 5/3
2007-06-04 23:29:05 · answer #2 · answered by Dr D 7 · 0⤊ 0⤋
B. 16x+12y=-15
First you have to isolate y
y= 3/4x-5/4
Then the line that is perpendicular has an opposite reciprocal slope (x)
So B:
12y=-15-16x
y=-15/12-16/12x
y=-5/4-4/3x
So this x= -4/3x (the opposite reciprocal)
2007-06-04 23:29:11 · answer #3 · answered by Jennifer 2 · 0⤊ 0⤋
Yes.
4y=3x-5 (Add 4y and subtract 5)
y=3/4x-5/4 (divide by 4)
y=-4/3x-5/4 (change the sign and use the reciprocal)
12y=-16x-15 (multiply by 12)
16x+12y=-15 (Add 16x)
It is B indeed
2007-06-04 23:25:28 · answer #4 · answered by llllarry1 5 · 0⤊ 0⤋
Yes the answer is B - the reason is to find a perpendicular line you have to invert the coefficients in front of x and y and interchange the signs. This is the case for B, but it is multiplied by a factor of 3. Just divide equation B by a factor of three and you'll see that it is exactly the coefficients switched with the sign changed. Hope this helps
2007-06-04 23:27:57 · answer #5 · answered by brix510 4 · 0⤊ 0⤋
Rearrage the equation to read...
y = 3/4*x - 5/4
The inverse has a negative reciprical for the slope...
y = -4/3*x -5/4
The answer for b appears to mulpiply this equation by 12..
12*y = -16*x - 15 now rearrange...
16*x + 12*y = -15
2007-06-04 23:33:44 · answer #6 · answered by Velkomen 2 · 0⤊ 0⤋
Of course you do!!! Any line perpendicular to a given line has a slope that is the negative reciprocal of the given line.
2007-06-04 23:28:44 · answer #7 · answered by cattbarf 7 · 0⤊ 0⤋
Yes.
I looked at the question and answers before I read your question, and my first thought was to put it in slope-intercept form to start.
2007-06-04 23:30:41 · answer #8 · answered by purple.minded 2 · 0⤊ 0⤋