展开-3(2x+5y=15)

解答

展开

- 3 (2 x + 5 y = 15)

- 6 x - 15 y = 15

求解步骤

- 3 (2 x + 5 y = 15)

= - 3 (2 x + 5 \cdot 15 = y)

使用分配律:

a (b + c) = ab + a c

a = - 3, b = 2 x, c = 5 y = 15

- 3 \cdot 2 x + (- 3) \cdot 5 y = 15

使用加减运算法则

+ (- a) = - a

- 3 \cdot 2 x - 3 \cdot 5 y = 15

乘开

- 3 \cdot 2 x - 3 \cdot 5 y : - 6 x - 15 y

- 6 x - 15 y = 15

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