Question

Sabendo que x+y = 10 e x-y = 4 determine o valor de x

a) 5x + 5y

b) 3x - 3y

c) x² + 2xy + y²

d) x² - 2xy + y²

Answer 1

X + Y = 10
X -  Y = 4
----------------
2X  //   = 14

X = 7 ******

7 + Y  = 10
Y = 10 - 7
Y = 3 ****

5X + 5Y =  5(7) + 5(3) = 35 + 15 = 50 ***

3X - 3Y = 3(7) - 3 ( 3 ) = 21 - 9 = 12 ****

X² + 2XY + Y² = ( 7)² + 2 * 7 * 3 + (3)²  = 49 +42 + 9 = 100 ****

X² - 2XY + Y² = 7² -  2*7*3 + 3²   = 49 - 42 + 9 = 16 *****