展开 (a+c=40,0)(25a+15c=7550)

解答

展开

(a + c = 40, 0) (25 a + 15 c = 7550)

25 a^{2} + 15 a c = 7550

求解步骤

(a + c = 40, 0) (25 a + 15 c = 7550)

= (a + 40 \cdot 0 =, c) (25 a + 15 \cdot 7550 = c)

使用 FOIL 方法:

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

a = a, b = c = 40, 0, c = 25 a, d = 15 c = 7550

a \cdot 25 a + a \cdot 15 c = 7550 + c = 40, 0 \cdot 25 a + c = 40, 0 \cdot 15 c = 7550

25 aa + 15 a c = 7550 + c = 40, 0 \cdot 25 a + c = 40, 0 \cdot 15 c = 7550

乘开

25 aa + 15 a c : 25 a^{2} + 15 a c

25 a^{2} + 15 a c = 7550

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