by: nora r.. problem suppose x and y are real numbers such that xy = 9 and x²y + xy² + x + y =...
TRANSCRIPT
By: Nora R.
POD Week #21
Problem #2
Problem
Suppose x and y are real numbers such that xy = 9 and x²y + xy² + x + y = 100. What is the integer value of x² + y²?
Problem:
First Step:
The first thing I did was try to figure out what I had to multiply x and y by to get 9.
I knew the product of x and y (xy) had to be 9 because it says in the problem that xy equals 9.
Second Step:
I know that since xy equals 9 I have to multiply two numbers to get 9.
So, I have two options, I can multiply 9×1 or 3×3. I guessed 9×1 first.
Third Step: So now what I did was solve the problem given (x²y + xy² + x + y) Since it doesn’t really matter what each variable is I just made
x=9 and y=1 So, now the new problem is - 9²(1) + 9(1)² + 9 + 1 - and I want to
see if this will equal 100.
Solving the Equation:
To solve this problem I just figured out what each section equals and then added them up to see if it equaled 100.
9²(1) + 9(1)² + 9 + 1 = ?9²= 8181 × 1 = 81
In the order of operations exponents come before multiplication so I have to do the exponent before multiplying anything, which pretty much means I have to do 1² first, then multiply that by 9. (PEMDAS)
1²= 11×9= 9
Fourth Step:
I added up all the numbers I got from the problem, to see if it equaled 100.
When I added them up, it did equal 100, so I knew I had the right numbers for x and y.
81 9 9 1 + 100
Final Step:
Now all I have to do to get my answer is solve the last problem giving with the variables I now have. (x=9, y=1)
The problem asked for me to solve the problem – x² + y² So I replace the variables with 9 and 1 to find the answer.
9² + 1²81 181 +1 = 82
Answer:
Once I solved that problem of 9² + 1² I got and answer of 82.
Any Questions?