Answer:
18
Step-by-step explanation:
54/9 + 12
6 + 12
= 18
Answer:
(x+a)²-7=x²+10x+b
simplifying,we get
x²+2ax+a²-7=x²+10x+b
the coefficient of x on both sides should be equal
therefore
2a=10
a=10/2=5
also for b
a²-7=b
5²-7=25-7=b
b=18
a=5
This question is the application of differential eqns in order to derive a model for the temperature dependence with time. Actually, a general equation has already been derived for this type of cases. This equation is known as the Newton's Law of Cooling. The equation is
(T - Ts) / (To -Ts) = e^(-kt)
where T is the the temperature at any time t
Ts is the surrounding temperature
To is the initial temperature
k is the constant
t is the time
several assumptions have been made to arrive at this form, i suggest you trace the derivation of the general formula.
First we need to look for k using the initial conditions that is @t = 1.5 min, T = 50 F
substituting we get a k = 0.2703
therefore @ t = 1 min, T = 55.79 F
@ T = 15 F the time required is 9.193 min.
