Answer:
la respuesta es la primera ( a )
Step-by-step explanation:
Ah okay so in differential equations you usually want the top variable isolated. To do this, multiply by dt and 2u and you get

Now just integrate both sides. The integral of 2u with respect to u is u². The integral of (2t + sec²(t) with respect to t is t² + ∫sec²(t)dt. The last part is just tan(x) because d/dt(tan(t)) is sec²(t) so just integrating gets us back. Now we have

Where c and k are arbitrary constants. Subtracting c from k and you get

Where b is another constant. To find b, just plug in u(0) = -1 where u is -1 and t is 0. This becomes

tan(0) is 0 so b = 1. Take the plus or minus square root on both sides and you finally get

But Brainly didn't let me do but juat remember there is a plus or minus square root on the left.
To find out of a graph is linear you have to use the vertical line test.
Answer:
(a) 2 degree celsius per hour
(b) 3 degree celsius per hour.
Step-by-step explanation:
From the question,
(a) Avearge rate of rise in temperature per hour(T') = Rise in temperature(T)/Time required for the rise(t).
T' = T/t.................... Euqation 1
Rise in temperature (T) = 4 degree celsius, t = 10.00 am to noon = 2 hours.
Substitute into equation 1
T' = 4/2
T' = 2 degree celsius per hour.
(b) Also,
Average rate of fall in temperature per hour (T') = Fall in temperature (T)/Time(t)
T' = T/t
Given: T = 6 degree celsius, t = 3:00 pm to 5:00 pm = 2 hours
T' = 6/2
T' = 3 degree celsius per hour
120% of 37 is 44.4. Good luck!