Welcome to the free online calculator to find two numbers by sum and sum of squares. For example, the sum of two numbers is 17 and the sum of their squares is 145. What are the numbers?
How to find two numbers based on the sum and sum of squares
Assuming these two numbers are x and y.
Then, we can get two equations based on the above problem description.
x + y = 17………(1)
x2 + y2 = 145………(2)
Simplify the first equation, let x be represented by y.
x = 17 – y
Substitute x = 17 - y into the second equation and simplify.
x2 + y2 = 145
(17 – y)2 + y2 = 145
289 – 34y + y2 + y2 = 145
2y2 – 34y + 289 = 145
2y2 – 34y + 144 = 0
y2 – 17y + 72 = 0
Now, we get a quadratic equation, the next key is to solve this quadratic equation. The answer to the quadratic equation can be calculated using the formula method or the factorization method. The quadratic formula is
Among them, a = 1, b = -17, c = 72. So, we can get the value of y
b2 – 4ac = (-17)2 – 4 * 1 * 72 = 289 – 288 = 1
y = -(-17) + √12*1 = 17 + 12 = 9
Or
y = -(-17) – √12*1 = 17 – 12*1 = 8
Or use the factorization method directly.
y2 – 17y + 72 = 0
(y – 8) (y – 9) = 0
y = 8 or y = 9
Both methods can calculate the value of y.
When y = 8, according to the relationship between x and y, we can calculate the value of x.
x = 17 – y = 17 – 8 = 9
When y = 9, the same operation can be used to calculate x = 8.
Therefore, the two numbers are 8 and 9.
Is it right or not? Check it out!
8 + 9 = 17
82 + 92 = 64 + 81 = 145
Yes, this is correct.
Of course, if you don’t want to calculate quadratic equations, we can think differently.
Square both sides of the first equation and simplify.
x + y = 17
(x + y)2 = 172
x2 + 2xy + y2 = 289
Then subtract the second equation from this new equation.
(x2 + 2xy + y2) – (x2 + y2) = 289 – 145
x2 + 2xy + y2 – x2 – y2 = 144
2xy = 144
xy = 72
Did you find anything?
Yes, x + y = 17, xy = 72. The question becomes, the sum of two numbers is 17 and their product is 72. What are the numbers? For specific solutions, see Find Two Numbers by Sum and Product Calculator.
In conclusion, solving such problems is not difficult, but requires simple and tedious calculations. So, we developed this free online calculator to find two numbers by sum and sum of squares. The calculator omits all steps and displays the answer in milliseconds.
Next, we will introduce how to use the calculator.
How to use the calculator to find two numbers by sum and sum of squares
Using the calculator is simple, follow these 3 steps:
- Enter the sum in the first input box.
- Enter the sum of squares in the second input box.
- Click Calculate button to get the answer, or click Reset button to start a new calculation.
Next, let’s look at some examples.
Solved examples using the calculator to find two numbers by sum and sum of squares
Example 1: The sum of two numbers is 20 and the sum of their squares is 208. What are the numbers?
Enter 20 in the first input box.
Enter 208 in the second input box.
Then click Calculate button, as shown in the figure, the two numbers are 8 and 12.
8 + 12 = 20
82 + 122 = 64 + 144 = 208
Example 2: The sum of two numbers is 25 and the sum of their squares is 325. What are the numbers?
Enter 25 in the first input box.
Enter 325 in the second input box.
Then click Calculate button, as shown in the figure, the two numbers are 10 and 15.
10 + 15 = 24
102 + 152 = 100 + 225 = 325
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