Hi there!
![\large\boxed{\text{At (-1, -2), }\frac{dy}{dx} = -\frac{2}{5}}}](https://tex.z-dn.net/?f=%5Clarge%5Cboxed%7B%5Ctext%7BAt%20%28-1%2C%20-2%29%2C%20%7D%5Cfrac%7Bdy%7D%7Bdx%7D%20%3D%20-%5Cfrac%7B2%7D%7B5%7D%7D%7D)
![\large\boxed{\text{At (-1, 3), }\frac{dy}{dx} = -\frac{3}{5}}}](https://tex.z-dn.net/?f=%5Clarge%5Cboxed%7B%5Ctext%7BAt%20%28-1%2C%203%29%2C%20%7D%5Cfrac%7Bdy%7D%7Bdx%7D%20%3D%20-%5Cfrac%7B3%7D%7B5%7D%7D%7D)
We can calculate dy/dx using implicit differentiation:
xy + y² = 6
Differentiate both sides. Remember to use the Product Rule for the "xy" term:
(1)y + x(dy/dx) + 2y(dy/dx) = 0
Move y to the opposite side:
x(dy/dx) + 2y(dy/dx) = -y
Factor out dy/dx:
dy/dx(x + 2y) = -y
Divide both sides by x + 2y:
dy/dx = -y/x + 2y
We need both x and y to find dy/dx, so plug in the given value of x into the original equation:
-1(y) + y² = 6
-y + y² = 6
y² - y - 6 = 0
(y - 3)(y + 2) = 0
Thus, y = -2 and 3.
We can calculate dy/dx at each point:
At y = -2: dy/dx = -(-2) / -1+ 2(-2) = -2/5.
At y = 3: dy/dx = -(3) / -1 + 2(3) = -3/5.
Answer:
1&a 2&b 3&c 4&d
Step-by-step explanation:
...
![x+y=k\implies y=k-x](https://tex.z-dn.net/?f=x%2By%3Dk%5Cimplies%20y%3Dk-x)
Substitute this into the parabolic equation,
![k-x=6-(x-3)^2\implies x^2-7x+(k+3)=0](https://tex.z-dn.net/?f=k-x%3D6-%28x-3%29%5E2%5Cimplies%20x%5E2-7x%2B%28k%2B3%29%3D0)
We're told the line
intersects
twice, which means the quadratic above has two distinct real solutions. Its discriminant must then be positive, so we know
![(-7)^2-4(k+3)=49-4(k+3)>0\implies k](https://tex.z-dn.net/?f=%28-7%29%5E2-4%28k%2B3%29%3D49-4%28k%2B3%29%3E0%5Cimplies%20k%3C%5Cdfrac%7B37%7D4%3D9.25)
We can tell from the quadratic equation that
has its vertex at the point (3, 6). Also, note that
![-1\le\sin t\le1\implies3\le3+2\sin t\le5\implies3\le x\le5](https://tex.z-dn.net/?f=-1%5Cle%5Csin%20t%5Cle1%5Cimplies3%5Cle3%2B2%5Csin%20t%5Cle5%5Cimplies3%5Cle%20x%5Cle5)
and
![-1\le\cos2t\le1\implies2\le4+2\cos2t\le6\implies2\le y\le6](https://tex.z-dn.net/?f=-1%5Cle%5Ccos2t%5Cle1%5Cimplies2%5Cle4%2B2%5Ccos2t%5Cle6%5Cimplies2%5Cle%20y%5Cle6)
so the furthest to the right that
extends is the point (5, 2). The line
passes through this point for
. For any value of
, the line
passes through
either only once, or not at all.
So
; in set notation,
![\{k\mid 7\le k](https://tex.z-dn.net/?f=%5C%7Bk%5Cmid%207%5Cle%20k%3C9.25%5C%7D)
Answer:
$24
Step-by-step explanation:
original price of a dress = $30
discount = 20%
discount amount = discount% of original price
=20/100 * 30
=30/5
=$6
price that consumer will pay after discount = $30 - $6
=$24
Answer:
x = 60
Step-by-step explanation:
The formula for this kind of question is
Area of sector = x / 360 * pi * r^2 = 24*pi
x/360 * pi * 12^2 = 24 pi
x/360 * pi * 144 = 24 pi the pi s cancel out
x / 360 = 24/144 Multiply both sides by 360
x = 24 * 360/144
x = 60