Question

the sum of two numbers is 15 and the difference of their squares is 15. the difference of the numbers is??

Answer 1

x+y = 15 ; x = 15-y
x² - y² = 15 (eq.1)
(15-y)² - y² = 15
15² + y² -2.15.y - y² = 15
225 - 30y = 15
- 30y + 225-15 = 0
 - 30y + 210 = 0
-30y = -210
30y = 210
y = 210/ 30 = 7
now , putting y = 7 in eq. 1 ,
x² - (7)² = 15
x² - 49 = 15
x² =15 +49 = 64
so , x = √64 = 8
now , diffrernce of no. = x-y = 8-7 = 1
therefore , required answer is 1.

Answer 2

x+y = 15 ; x = 15-y the answer would be one 1.