展开 (x+1)(x-2)(x+4)(3x+7)

解答

展开

(x + 1) (x - 2) (x + 4) (3 x + 7)

3 x^{4} + 16 x^{3} + 3 x^{2} - 66 x - 56

求解步骤

(x + 1) (x - 2) (x + 4) (3 x + 7)

展开

(x + 1) (x - 2) (x + 4) (3 x + 7) : (x^{2} - x - 2) (x + 4) (3 x + 7)

= (x^{2} - x - 2) (x + 4) (3 x + 7)

Apply FOIL method

(x + 4) (3 x + 7) : 3 x^{2} + 19 x + 28

= (x^{2} - x - 2) (3 x^{2} + 19 x + 28)

打开括号

= x^{2} \cdot 3 x^{2} + x^{2} \cdot 19 x + x^{2} \cdot 28 - x \cdot 3 x^{2} - x \cdot 19 x - x \cdot 28 - 2 \cdot 3 x^{2} - 2 \cdot 19 x - 2 \cdot 28

化简

x^{2} \cdot 3 x^{2} + x^{2} \cdot 19 x + x^{2} \cdot 28 - x \cdot 3 x^{2} - x \cdot 19 x - x \cdot 28 - 2 \cdot 3 x^{2} - 2 \cdot 19 x - 2 \cdot 28 : 3 x^{4} + 16 x^{3} + 3 x^{2} - 66 x - 56

= 3 x^{4} + 16 x^{3} + 3 x^{2} - 66 x - 56

s im pl i f y \frac{7}{5 x - 2 a}

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