A. 3x + 4y - 36 = 0
B. 4x + 3y = 35
C. 3x - 4y + 30 = 0
D. 4x - 3y - 23 = 0
E. 3x + 4y + 14 = 0
F. 4x + 3y + 15 = 0
G. 3x - 4y - 20 = 0
H. 4x - 3y + 27 = 0
I. none of these
2006-07-17 05:54:52 · 5 answers · asked by Olivia 4 in Science & Mathematics ➔ Mathematics
First differentiate x^2 + y^2 - 2x - 4y = 20
Let the slope, dy/dx = m (say)
Which gives, 2x + 2ym -2 - 4m = 0
implies, m = (2 -2x) / (2y - 4) = (1 - x) / (y - 2)
As you want the tangent at (1,7) substitute it in this equation.
It gives the value of m, the slope as zero.
You know the slope and point so apply point-slope formula.
Which is (y - 7) = 0 (x - 1)
implies the line is y = 7 which is parallel to x-axis and at a distance of 7 units from it.
Hope you can understand this.
2006-07-17 07:06:14 · answer #1 · answered by Sherlock Holmes 6 · 5⤊ 0⤋
none of these
differentiating 2x+2y.dy/dx-2-4dy/dx=0
passes through (1,7),substituting
2+14dy/dx-2-4dy/dx=0=>dy/dx=0
slope of the tangent at(1,7)=0
equation of the tangent is
y-7=0(x-1) =>y=7
2006-07-17 13:18:54 · answer #2 · answered by raj 7 · 0⤊ 0⤋
I. None
Plug (1, 7) into each potential answer. None of them are true.
2006-07-17 13:00:34 · answer #3 · answered by jimvalentinojr 6 · 0⤊ 0⤋
y=7
it is the line tangent at the top of the circle
2006-07-17 13:00:46 · answer #4 · answered by Kris C 2 · 0⤊ 0⤋
Do your own homework!!
2006-07-17 12:59:14 · answer #5 · answered by ceprn 6 · 0⤊ 0⤋