4. If the determinant delta of a quadratic equation is positive, the equation has two real roots. If the determinant is negative, it has two imaginary roots. In this case, delta=b^2-4ac=(-1)^2-4*1*4=-15. Therefore, this equation has two imaginary roots.
y = x^2 + 5x -3
y-x =2
Replace y in the second equation with the first one:
x^2 + 5x -3 - x = 2
Simplify by combining like terms:
x^2 + 4x -3 = 2
Subtract 2 from both sides:
x^2 + 4x -5 = 0
Fctor the polynomial:
(x-1) (x+5) = 0
Solve for both X's:
x = 1 and x = -5
Now replace x in the second equation with both value and solve for y:
y -1 =2, y = 3
y - -5 =2, y +5 = 2, y = -3
Now combine the sets of answers:
(1,3) and (-5,-3)
Answer: A
Step-by-step explanation:
-2/3+(-4/6)
= -2/3 -2/3
=(-2-2)/3
=-4/3
Answer:
And we can find this probability with the following difference:
And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the number of gallons of a population, and for this case we know the distribution for X is given by:
Where
and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability with the following difference:
And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.