Answer:
13 ft/s
Step-by-step explanation:
t seconds after the boy passes under the balloon the distance between them is ...
d = √((15t)² +(45+5t)²) = √(250t² +450t +2025)
The rate of change of d with respect to t is ...
dd/dt = (500t +450)/(2√(250t² +450t +2025)) = (50t +45)/√(10t² +18t +81)
At t=3, this derivative evaluates to ...
dd/dt = (50·3 +45)/√(90+54+81) = 195/15 = 13
The distance between the boy and the balloon is increasing at the rate of 13 ft per second.
_____
The boy is moving horizontally at 15 ft/s, so his position relative to the spot under the balloon is 15t feet after t seconds.
The balloon starts at 45 feet above the boy and is moving upward at 5 ft/s, so its vertical distance from the spot under the balloon is 45+5t feet after t seconds.
The straight-line distance between the boy and the balloon is found as the hypotenuse of a right triangle with legs 15t and (45+5t). Using the Pythagorean theorem, that distance is ...
d = √((15t)² + (45+5t)²)
Answer:
820 
Step-by-step explanation:
Answer:
Hello,
in order to simplify, i have taken the inverses functions
Step-by-step explanation:
![\int\limits^\frac{1}{2} _{-1} {(-2x^2-x+1)} \, dx \\\\=[\frac{-2x^3}{3} -\frac{x^2}{2} +x]^\frac{1}{2} _{-1}\\\\\\=\dfrac{-2-3+12}{24} -\dfrac{-5}{6} \\\\\boxed{=\dfrac{9}{8} =1.25}\\](https://tex.z-dn.net/?f=%5Cint%5Climits%5E%5Cfrac%7B1%7D%7B2%7D%20_%7B-1%7D%20%7B%28-2x%5E2-x%2B1%29%7D%20%5C%2C%20dx%20%5C%5C%5C%5C%3D%5B%5Cfrac%7B-2x%5E3%7D%7B3%7D%20-%5Cfrac%7Bx%5E2%7D%7B2%7D%20%2Bx%5D%5E%5Cfrac%7B1%7D%7B2%7D%20_%7B-1%7D%5C%5C%5C%5C%5C%5C%3D%5Cdfrac%7B-2-3%2B12%7D%7B24%7D%20-%5Cdfrac%7B-5%7D%7B6%7D%20%5C%5C%5C%5C%5Cboxed%7B%3D%5Cdfrac%7B9%7D%7B8%7D%20%3D1.25%7D%5C%5C)
Answer:
3a. 8t + 12c = 72
3b. t + c = 7
Step-by-step explanation:
number of tapes is t
number of Cds is c
so 8t + 12c = 72
and t + c = 7
so t = 7 - c
replace t = 7 - c in to the first equation
8(7 - c) + 12c = 72
56 - 8c + 12c = 72
4c = 72 - 56 = 16
c = 4
if c = 4, then t = 7 - c = 7 - 4 = 3
Answer:
2:5
Step-by-step explanation:
david=24mins
mark = 1hour
change 1 hour to mins
DAVID=24
MARK=60
24:60
THEN SIMPLIFY
24/60
<em>=</em><em>2</em><em>/</em><em>5</em>
<em><u>2</u></em><em><u>:</u></em><em><u>5</u></em>
