Answer:
-8 & -7
Step-by-step explanation:
-8+-7=-15
-8*-7=56
Answer:
x(t) = 2000 - e^(-k*t)
Step-by-step explanation:
Interpretation:
No . infected student = x
Total student = 2000
rate of infected students = dx / dt
not-infected student = 200 - x
The general rate at which student are infected can be expressed as below:
dx / dt = k * ( 2000 - x )
To develop an expression of x(t) we integrate the above expression by separating variables:
dx / (2000 - x ) = k * dt
Now integrate:
@ t = 0 , infected students x = 0
Hence,
C = - ln (2000)
X²+15x+36<0
at first solve quadratic equation
D=b²-4ac= 225-4*1*36= 81
x=(-b+/-√D)/2a
x=(-15+/-√81)/2= (-15+/-9)/2
x1=(-15-9)/2=-12
x2=(-15+9)/2=-3
we can write x²+15x+36<0 as (x+12)(x+3)<0
(x+12)(x+3)<0 can be 2 cases, because for product to be negative one factor should be negative , and second factor should be positive
1 case) x+12<0, and x+3>0,
x<-12, and x>-3
(-∞, -12) and(-3,∞) gives empty set
or second case) x+12>0 and x+3<0
x>-12 and x<-3
(-12,∞) and (-∞,-3) they are crossing , so (-12, -3) is a solution of this inequality
Since the required number is between 234 and 250, then the first digit of the number is 2 and the second digit can either be 3 or 4.
Let the second and the third digits be x and y respectively, then
2 + x + y = 2y
Consider when the second digit is 3, then
2 + 3 + y = 2y
5 = y
Thus, the number is 235.
Similarly, consider when the second digit is 4, then
2 + 4 + y = 2y
6 = y
Thus, the number is 246.
Since the required number is an even number, therefore, Isabel's number is 246.
Eliminationg these equations gives zero ,no solution
