Question

Se x-y=8 e x+y=14 ,quanto vale X2 -Y2 ??

Answer 1

x = 8 + y

8 + y + y = 14

2y = 14 - 8

2y = 6

y = 6/2

y = 3

x - y = 8

x - 3 = 8

x = 8 + 3

x = 11

x2 - y2

11.2 - 3.2

22 - 6

16

Answer 2

Primeiro vamos resolve o sistema.


x - y = 8
x + y = 14
========
2x = 22
x = 22/2
x = 11

x + y = 14
11 + y = 14
y = 14 - 11
y = 3


X = 11
Y = 3


X² - Y²

11² - 3²
121 - 9 = 112