0
I think you probably want it the other way around: numbers that add to -9 and multiply to 20. These would be -4 and -5.
How you wrote it:
x + y = 20
xy = -9
x = 20 - y
(20 - y)y = -9
-y^2 + 20y = -9
y^2 - 20y - 9 = 0
(-(-20) +/- sqrt((-20)^2 - 4(1)(-9)))/(2(1)) = y
(20 +/- sqrt(436))/2
10 +/- 2sqrt(109)/2
10 +/- sqrt(109) = y
x + y = 20
x + (10 +/- sqrt(109) = 20
If +,
x + 10 + sqrt(109) = 20
x = 10 - sqrt(109)
If -,
x + 10 - sqrt(109) = 20
x = 10 + sqrt(109)
The two numbers are thus:
10 + sqrt(109) and 10 - sqrt(109)
Check:
x + y = 20
(10 + sqrt(109)) + (10 - sqrt(109)) = 20
10 + 10 + sqrt(109) - sqrt(109) = 20
20 = 20
xy = -9
(10 + sqrt(109))(10 - sqrt(109)) = -9
Difference of squares => (a+b)(a-b)=(a^2 - b^2)
10^2 - sqrt(109)^2 = -9
100 - 109 = -9
-9 = -9
The solutions do work, so the numbers are:
10 + sqrt(109) and 10 - sqrt(109)
Add your answer:
Earn +20 pts
What times together to Make 32 and add to make -12?
20
What two numbers add together to make -20 but times together to give 72?
-15.2915 and -4.7085 (approx).
What two number multiple together to make -60 and add together to get -17?
-77
When 3 times a certain number n is add to 6 the sum is 20 more then a origina number what is the number n?
In mathematical terms the problem is :- 3n + 6 = 20 + n 3n - n = 20 - 6 2n = 14 n = 7
When add 8 to me you get 20 What number am i?
12
Thrice a number and add two times the same number is equal to 100 what is the number?
20
what three two number add with 20 to make a 140?
Here is the answer 20 + 49 + 71= 140
6 Is a multiple of 20?
no tried timesing 6 by any number and you wont get 20 or you can add 6. 4 times youll see its not 20
What is 10000 times 20?
Just add up the number of zeroes from the '1' started number, like 10000. So, the answer is 200.000.
What times together to Make 32 and add to make -12?
20
What two numbers add together to make -20 but times together to give 72?
-15.2915 and -4.7085 (approx).
What two number multiple together to make -60 and add together to get -17?
-77
Using the number 4 four times can you make 1-20?
((4/4) + 1) * 4=20
How do you add 20 percent to a number?
To add 20 percent to a number, multiply the number by 1.2. For example, adding 20 percent to 50 gives 50 x 1.2 = 60.
How do you find how many boys there are in a school of 340 students if you know the ratio is 8 to 9 girls to boys?
First add 8 and 9 to get 17. Then divide 340 by 17 to get 20. Then times 20 by 8 to find the number of girls or times 20 by 9 to get the number of boys. Number of girls: 160 Number of boys: 180
When 3 times a certain number n is add to 6 the sum is 20 more then a origina number what is the number n?
In mathematical terms the problem is :- 3n + 6 = 20 + n 3n - n = 20 - 6 2n = 14 n = 7
What number should you add to -8 to get plus 12?
You add 20
