Speed, S = Distance (d) / Time (t) => S= d/t => t= d/S
Let the speed of boat in still water be x mph
Resulting speed upstream = x-4 mph for a distance of 30 miles
Resulting speed downstream = x-4 mph for a distance of 50 miles
Time taken in both distances is equal.
Therefore,
30/(x-4) = 50/(x+4) => 30(x+4) = 50(x-4) => 30x+120 = 50x-200 => 120+200 = (50-30)x => 20x = 320 => x=320/20 = 16 mph
The speed of boat in still water is 16 mph.
(2.0×10^-4)×(3.1×10^-20)
=(2.0×3.1)×(10^4×10^-20)
=6.2×10^(-4+(-20))
=6.2×10^-24. Hope it help!
D dddddddddddddddddddddfdfddxdddd
1/9
Here's the proper explanation:
Since the vertex is (2,-1), the original equation will look like this: y=a*(x-2)^2-1
When the substitution happens we get to this:
0=a*(5-2)^2-1 then 1=a*(5-2)^2 -> 1=a*9
So, a=1/9! Written in another form:
1/9x^2-4/9x+4/9-1
Hope could help :)
