展开-2(5x+3y=21)

解答

展开

- 2 (5 x + 3 y = 21)

- 10 x - 6 y = 21

求解步骤

- 2 (5 x + 3 y = 21)

= - 2 (5 x + 3 \cdot 21 = y)

使用分配律:

a (b + c) = ab + a c

a = - 2, b = 5 x, c = 3 y = 21

- 2 \cdot 5 x + (- 2) \cdot 3 y = 21

使用加减运算法则

+ (- a) = - a

- 2 \cdot 5 x - 2 \cdot 3 y = 21

乘开

- 2 \cdot 5 x - 2 \cdot 3 y : - 10 x - 6 y

- 10 x - 6 y = 21

e x p an d ln (q) (- \frac{1}{a} - 1) - ln (- a)

e x p an d \frac{20 ( 41 - 2 x )}{3}

e x p an d (x - 3) (x + 1) \circ (6 x - 2)

e x p an d \frac{1}{z ( 1 + z )}

e x p an d - \frac{( x + 7 ) ( x - 4 )}{18}