Find the point on the line 6x + y = 8 that is closest to the point (−5, 2).(x, y) =
1 answer:
9514 1404 393
Answer:
(x, y) = (31/37, 2 36/37) ≈ (0.8378, 2.9730)
Step-by-step explanation:
There are several ways we can go at this.
<u>Method 1</u>
Find the point of intersection with the perpendicular line through (-5, 2).
The perpendicular line will have the x- and y-coefficients swapped, one of them negated, and a new constant consistent with the given point.
x -6y = (-5) -6(2) = -17
So, we're looking for the solution of the system of equations ...
- 6x +y = 8
- x -6y = -17
Using Cramer's Rule, we can find the solution to be ...
x = ((1)(-17) -(-6)(8))/((1)(1) -(-6)(6)) = 31/37 ≈ 0.837_837*
y = ((8)(1)-(-17)(6))/37 = 110/37 ≈ 2.972_972
The closest point is (x, y) = (31/37, 2 36/37).
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<u>Method 2</u>
We can write the given line in parametric form, then find the point on it such that the direction along the line is perpendicular to the direction to the given point.
Solving the given equation for y, we have ...
y = 8 -6x
So, the parametric form of the given line can be written as ...
(x, y) = (0, 8) +t(1, -6) . . . . for some parameter t
The direction to the given point from (x, y) is then ...
(-5, 2) -(x, y) = (-5, 2) -((0, 8) +t(1, -6)) = (-5-0-t, 2-8+6t) = (-t-5, 6t-6)
The dot-product of this direction vector with the direction vector of the original line will be zero for the value of the parameter at the closest point.
(1, -6) · (-t-5, 6t-6) = 0 = (1)(-t -5) +(-6)(6t -6)
0 = -t -5 -36t +36 = -37t +31
31/37 = t
So, filling this value into the parametric equation gives the closest point as ...
(0, 8) +(31/37)(1, -6) = (31/37, 2 36/37) = (x, y)
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<u>Method 3</u>
Find the point of tangency of the given line with a circle centered at (-5, 2).
The equation of a circle centered at (-5, 2) is ...
(x +5)^2 +(y -2)^2 = r^2
The given line will meet the circle at a point that satisfies this equation and the equation of the circle. Writing an expression for y using the given line, we can substitute into the circle equation to get ...
(x +5)^ +((8 -6x) -2)^2 = r^2
x^2 +10x +25 +36 -72x +36x^2 = r^2
37x^2 -62x + (some constant) = 0
This will have one solution when the constant is chosen to make the left-side expression a perfect square. That perfect square will be ...
37(x -31/37)^2 = 0
which is to say the tangent point of the line and the circle will have x-coordinate x = 31/37. The y-coordinate is 8 -6(31/37) = 2 36/37.
The closest point is (x, y) = (31/37, 2 36/37).
_____
* repeated decimal fractions are signified in typeset text with an overbar over the repeating digits. In plain text, we sometimes use a preceding underscore to identify the repeating digits.
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Question:
Which scenario best matches the linear relationship expressed in the equation y = –14x + 1,700?
1) Kent has $1,700 in his bank account and spends $14 each week.
2) Kent has $1,700 in his bank account and deposits $14 each week.
3) Kent had $1,700 in his bank account and deposited another $14.
4) Kent has $14 in his bank account and spent $1,700.
Answer:
Option 1) Kent has $1,700 in his bank account and spends $14 each week.
Step-by-step explanation:
Let x denote the number of weeks.
Option 1: Kent has $1,700 in his bank account and -14x as the negative sign denotes how much amount he spend each week.
Thus, Option 1 is the correct answer.
Option 2: Kent has $1,700 in his bank account and deposits $14 each week.
Writing it as equation, we have, which is not the expressed linear equation.
Hence, Option 2 is not the correct answer.
Option 3: Kent had $1,700 in his bank account and deposited another $14.
Writing it as equation, we have, which is not the expressed linear equation.
Hence, Option 3 is not the correct answer.
Option 4: Kent has $14 in his bank account and spent $1,700.
Writing it as equation, we have, which is not the expressed linear equation.
Hence, Option 4 is not the correct answer.
Thus, the scenario that matches the linear equation relationship expressed in the equation is Option 1.
The answer is Kent has $1,700 in his bank account and spends $14 each week.