展开 (x+8y=9,)(-3x-5y=12)

解答

展开

(x + 8 y = 9,) (- 3 x - 5 y = 12)

- 3 x^{2} - 5 x y = 12

求解步骤

(x + 8 y = 9,) (- 3 x - 5 y = 12)

= (x + 8 \cdot 9 =, y) (- 3 x - 5 \cdot 12 = y)

使用 FOIL 方法:

(a + b) (c + d) = a c + a d + b c + b d

a = x, b = 8 y = 9,, c = - 3 x, d = - 5 y = 12

x (- 3 x) + x (- 5 y = 12) + 8 y = 9, (- 3 x) + 8 y = 9, (- 5 y = 12)

使用加减运算法则

+ (- a) = - a

- 3 xx - 5 x y = 12 - 8 y = 9, 3 x - 8 y = 9, 5 y = 12

乘开

- 3 xx - 5 x y : - 3 x^{2} - 5 x y

- 3 x^{2} - 5 x y = 12

e x p an d \frac{4 ^{3}}{5 ^{3}}

e x p an d (x + 3 + 4 i) (x + 3 - 4 i) (x - 15)

e x p an d (9 + i)^{5}

e x p an d (x - 1) (x - 1 + 3)

e x p an d X (F (X) X + 1 = + 1)