Answer:
A and B are correct
Step-by-step explanation:
Quadratic equations CAN be used to solve word problems so the answer to your question is false
Answer: the option A.
The elimination method consist is adding the two equations in a way that one variable be eliminated..
In order to do that you might have to manipulate on of the equations prior to add the two equations.
In this case, ff you multiply the second equation by - 1 you will get
- x - y = - 4
which you can add to the first equation
2x + y = 8 to eliminate the y.
Answer:
a) 
b) 
Step-by-step explanation:
Previous concepts
The exponential distribution is "the probability distribution of the time between events in a Poisson process (a process in which events occur continuously and independently at a constant average rate). It is a particular case of the gamma distribution". The probability density function is given by:

And 0 for other case. Let X the random variable that represent "life lengths of automobile tires of a certain brand" and we know that the distribution is given by:

The cumulative distribution function is given by:

Part a
We want to find this probability:
and for this case we can use the cumulative distribution function to find it like this:

Part b
For this case w want to find this probability

We have an important property on the exponential distribution called "Memoryless" property and says this:
On this case if we use this property we have this:
We can use the definition of the density function and find this probability:
