Question

Sabendo que x + y = 15 e x – y = 13, então calcule:
a) 5x - 5y=
b) x² - y² =
c) 6x + 6y + 2x + 2y =
d) x² - 2xy + y²=

Answer 1

Resposta:

$\textsf{Leia abaixo}$

Explicação passo-a-passo:

$\begin{cases}\sf x + y = 15\\\sf x - y = 13\end{cases}$

$\sf 2x = 28$

$\boxed{\boxed{\sf x = 14}}$

$\sf 14 - y = 13$

$\sf y = 14 - 13$

$\boxed{\boxed{\sf y = 1}}$

$\sf a)\: 5x - 5y = 5(14) - 5(1) = 70 - 5 = 65$

$\sf b)\: x^2 - y^2 = 14^2 - 1^2 = 196 - 1 = 195$

$\sf c)\: 6x + 6y + 2x + 2y = 6(14) + 6(1) + 2(14) + 2(1) = 84 + 6 + 28 + 2 = 120$

$\sf d)\: x^2 - 2xy + y^2 = (x - y)^2 = (14 - 1)^2 = 13^2 = 169$

Answer 2

x - y = 13

x = 13 + y

x + y = 15

( 13 + y ) + y = 15

2 y = 15 - 13

y = 2 / 2 = 1

x - 1 = 13

x = 13 + 1

x = 14

a) 5 * 14 - 5 * 1 = 70 - 5 = 65

b) 14² - 1² = 196 - 1 = 195

c) 6 * 14 + 6 * 1 + 2 * 14 + 2 * 1 = 84 + 6 + 28 + 2 = 120

d) 14² - 2 * 14 * 1 + 1² = 196 - 28 + 1 = 169