展开 (3x-y=4,)(x+y=3)

解答

展开

(3 x - y = 4,) (x + y = 3)

3 x^{2} + 3 x y = 3

求解步骤

(3 x - y = 4,) (x + y = 3)

= (3 x - 4 =, y) (x + 3 = y)

使用 FOIL 方法:

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

a = 3 x, b = - y = 4,, c = x, d = y = 3

3 xx + 3 x y = 3 + (- y = 4,) x + (- y = 4,) y = 3

使用加减运算法则

+ (- a) = - a

3 xx + 3 x y = 3 - y = 4, x - y = 4, y = 3

乘开

3 xx + 3 x y : 3 x^{2} + 3 x y

3 x^{2} + 3 x y = 3

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