Answer:
18 to 2
Step-by-step explanation:
So 7 x = x2 -18 so you get the quadratic x^2 -7x -18 and then get 2 x -9= -18 and 2 + -9 = -7 so you get (x + 2) ( x - 9) so the positive solution would be x-9 = 0 so x= 9. Hope this helps :)
Answer:
C) 2+7i is the correct answer.
Step-by-step explanation:
simplify by combining the real and imaginary parts of each expression. in this question, the variable i represents an imaginary number.
Answer: C 4
Step-by-step explanation:
Use the formula: distance = rate x time
We can say that train 1 travels a distance of x, and train 2 travels a distance of 700 - x
The rate of train 1 is 75 mph, and the rate of train 2 is 100 mph
The time traveled for the two trains will be the same. We can represent that with the variable t.
We have the following equation for train 1:
x = 75t
For train 2, we have this equation:
700 - x = 100t
Use the Substitution Method by replacing x in the equation for train 2 with the value 75t.
700 - 75t = 100t
700 = 175t
700/175 = 4 hours.
It will take 4 hours for the two trains to meet.
Answer: c. z = 1.35; Reject the null hypothesis
Step-by-step explanation:
Let
be the average life expectancy of its batteries.
As per given , we have
Null hypothesis : 
Alternative hypothesis : 
Since
is right-tailed and population standard deviation is also known, so we perform right-tailed z-test.
Test statistic : 
where, n= sample size
= sample mean
= Population mean
=population standard deviation
For
, we have

Critical one-tailed test value for 0.10 significance level :

Decision : Since critical z value (1.28) < test statistic (1.35), so we reject the null hypothesis .
[When critical value is less than the test statistic value , we reject the null hypothesis .]