Question

The sum of any two number is 21and the sum of their squares is 261.find the numbers.​

Answer 1

Answer:

The two numbers are 6 and 15.

Step-by-step explanation:

$x+y=21\\y=21-x\\x^{2} +y^{2} =261\\x^{2} +(21-x)^{2}=261\\x^{2} +441-42x+x^{2} =261\\2x^{2} -42x+180=0\\x^{2} -21x+90=0\\(x-6)(x-15)=0$

x=6 and x=15