Answer:
A
Step-by-step explanation:
Given
x² - x = 30
To complete the square
add ( half the coefficient of the x- term )² to both sides
x² + 2(- 
)x + 
= 30 +
(x - )² = 
Take the square root of both sides
x - = ± 
= ± 
Add to both sides
x = ± , thus
x = - = - 5
x = + = 6
Answer:
C = 2
Step-by-step explanation:
9c + 14 = 2c^2 + 9c + 6
-9c -9c
14 = 2c² + 6
-6 -6
8 = 2c²
4 = c²
c = 2
The equation of the required plane can be obtained thus:
-4(x + 1) + 4(y + 3) + 3(z - 1) = 0
-4x - 4 + 4y + 12 + 3z - 3 = 0
4x - 4y - 3z = 5
Let x = 1, y = 2, then 4(1) - 4(2) - 3z = 5
z = (4 - 8 - 5)/3 = -9/3 = -3
Thus, point (1, 2, -3) is a point on the plane.
Let a = (a1, a2, a3) and b = (b1, b2, b3) be vectors parallel to the plane.
Then, -4a1 + 4a2 + 3a3 = 0 and -4b1 + 4b2 + 3b3 = 0
Let a1 = 2, a2 = -1, then a3 = (4(2) - 4(-1))/3 = (8 + 4)/3 = 12/3 = 4 and let b1 = -1 and b2 = 2, then b3 = (4(-1) - 4(2))/3 = (-4 - 8)/3 = -12/3 = -4
Thus a = (2, -1, 4) and b = (-1, 2, -4)
Therefore, the required parametric equation is r(s, t) = s(2, -1, 4) + t(-1, 2, -4) + (1, 2, -3) = (2s, -s, 4s) + (-t, 2t, -4t) + (1, 2, -3) = (2s - t + 1, -s + 2t + 2, 4s - 4t - 3)
Answer:
0.620
Step-by-step explanation:
We know that 1 feet = 12 inches, so, 5 feet is equivalent to 60 inches. Then, we are looking for the probability that a typical female from this population is between 60 inches and 67 inches. We know that
= 65.7 inches and
= 3.2 inches
and the normal density function for this mean and standard deviation is
![\frac{1}{\sqrt{2\pi } 3.2}exp[-\frac{(x-65.7)^{2}}{2(3.2)^{2}} ]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B%5Csqrt%7B2%5Cpi%20%7D%203.2%7Dexp%5B-%5Cfrac%7B%28x-65.7%29%5E%7B2%7D%7D%7B2%283.2%29%5E%7B2%7D%7D%20%5D%20)
The probability we are looking for is given by
![\int\limits^{67}_{60} {\frac{1}{\sqrt{2\pi } 3.2}exp[-\frac{(x-65.7)^{2}}{2(3.2)^{2}} ] } \, dx =0.620](https://tex.z-dn.net/?f=%5Cint%5Climits%5E%7B67%7D_%7B60%7D%20%7B%5Cfrac%7B1%7D%7B%5Csqrt%7B2%5Cpi%20%7D%203.2%7Dexp%5B-%5Cfrac%7B%28x-65.7%29%5E%7B2%7D%7D%7B2%283.2%29%5E%7B2%7D%7D%20%5D%20%7D%20%5C%2C%20dx%20%3D0.620)
You can use a computer to calculate this integral. You can use the following instruction in the R statistical programming language
pnorm(67, 65.7, 3.2)-pnorm(60, 65.7, 3.2)
