A car completes a journey at an average speed of 40km/h.At what speed must it travel on the return journey if the average speed
1 answer:
You might be interested in
Answer:
6.46
Step-by-step explanation:
h(t) = (1/2) + v0t + h0
Origin is at surface of water (h = 0), up is positive.
a = -g = -9.8 m/
v0 = 25 m/s
h0 = 50 m
h(t) = -4.9t2 + 25t + 50
Find t when
7 = + 25t + 50
- 25t - 43 = 0
t = [1/(2*4.9)] [25 ±√( + 4*4.9*43)]
t = (0.102)(25 ± 38.312)
t > 0 ⇒ use only the positive square root
t = (0.102)(25 + 38.312) ≅ 6.46 s
It is 7m above the water at about 6.46 s
Answer:
12x +8y +1 = 0
Step-by-step explanation:
You can write the equation by swapping the x- and y-coefficients and negating one of them. Then compute the constant that makes the line go through the given point. You can do that like this:
3(x-(-3/4)) +2(y -1) = 0
3x +9/4 +2y -2 = 0 . . . . eliminate parentheses
3x +2y +1/4 = 0 . . . . . . . simplify
To eliminate the fraction, multiply by 4:
12x +8y +1 = 0
_____
<em>Comment on the equation</em>
The line ax+by=0 passes through the origin. Replacing x and y with x-h and y-k, respectively, makes the line pass through the point (h, k). That's what we did above to make the line pass through the given point.
The business of swapping coefficients and negating one causes the slope of the new line to be the negative reciprocal of the slope of the original line. That is what makes the new line perpendicular to the original.
