For quadratics, these formulas are used mainly for factoring.
Your equation can be written as ...
... 2(x² +2x -3) = 0
You factor this by looking for factors of -3 (c=x1·x2) that add to give +2 (b=-(x1+x2)). These are {-1, +3}, so the factorization is ...
... 2(x -1)(x +3) = 0
The roots are then 1 and -3, which sum to -b = -2.
(You will note that the numbers used in the binomial factors are the opposites of the roots x1 and x2 in the Viete's Formulas. That is how we can look for them to sum to "b", rather than "-b".)
To prove this inequality we need to consider three cases. We need to see that the equation is symmetric and that switching the variables x and y does not change the equation.
Case 1: x >= 1, y >= 1
It is obvious that
x^y >= 1, y^x >= 1
x^y + y^x >= 2 > 1
x^y + y^x > 1
Case 2: x >= 1, 0 < y < 1
Considering the following sub-cases:
- x = 1, x^y = 1
- x > 1,
Let x = 1 + n, where n > 0
x^y = (1 + n)^y = f_n(y)
By Taylor Expansion of f_e(y) around y = 0,
x^y = f_n(0) + f_n'(0)/1!*y + f_n''(0)/2!*y^2 + ...
= 1 + ln(1 + n)/1!*y + ln(1 + n)^2/2!*y^2 + ...
Since ln(1 + n) > 0,
x^y > 1
Thus, we can say that x^y >= 1, and since y^x > 0.
x^y + y^x > 1
By symmetry, 0 < x < 1, y >= 1, also yields the same.
Case 3: 0 < x, y < 1
We can prove this case by fixing one variable at a time and by invoking symmetry to prove the relation.
Fixing the variable y, we can set the expression as a function,
f(x) = x^y + y^x
f'(x) = y*x^(y-1) + y^x*ln y
For all x > 0 and y > 0, it is obvious that
f'(x) > 0.
Hence, the function f(x) is increasing and hence the function f(x) would be at its minimum when x -> 0+ (this means close to zero but always greater than zero).
lim x->0+ f(x) = 0^y + y^0 = 0 + 1 = 1
Thus, this tells us that
f(x) > 1.
Fixing variable y, by symmetry also yields the same result: f(x) > 1.
Hence, when x and y are varying, f(x) > 1 must also hold true.
Thus, x^y + y^x > 1.
We have exhausted all the possible cases and shown that the relation holds true for all cases. Therefore,
<span> x^y + y^x > 1
----------------------------------------------------
I have to give credit to my colleague, Mikhael Glen Lataza for the wonderful solution.
I hope it has come to your help.
</span>
Number of adults = 264
Number of children= 127
Step-by-step explanation:
Let the number of adults be......x
Let the number of children be.....y
The total number of people that used the public swimming pool is given as 391. This means
x+y=391
The total cost per the receipt is : $752.75
This means, 2.25 x+ 1.25 y = 752.75
The two equations are;
x+y=391 ...........(i)
2.25 x+ 1.25 y = 752.75...........(ii)
Making the x variable equal to eliminate x
2.25x + 2.25 y = 879.75
2.25x + 1.25 y = 752.75
Apply subtraction as
1.00 y = 127.00
y=127
Use the value of y in equation (i)
x+y=391
x+127=391
x=391-127=264
Number of adults = 264
Number of children= 127
Learn More
Simultaneous equations: brainly.com/question/12318095
Keywords ; public, swiming pool, prices, daily, adults, children, receipt, admission
#LearnwithBrainly
Answer:
She is correct because 30 percent of 30 is 9 or in other words if you multiply 30 by 30 percent you get 9.
Step-by-step explanation:
Hey there!
Combine Like Terms and see if the expressions are equivalent or not.
6x-4-x
6x-x-4
5x-4
Is 5x-4 equivalent to 7x-4? No.
Hope everything is clear.
Let me know if you have any questions!
Always remember: Knowledge is power!