làm tròn là 1 nhé

P(x)+Q(x)−R(x)

Với các đa thức đã cho:

• \(P \left(\right. x \left.\right) = 3 x - 2 x^{2} - 2 + 6 x^{3}\)
• \(Q \left(\right. x \left.\right) = 3 x^{2} - x - 2 x^{3} + 4\)
• \(R \left(\right. x \left.\right) = 1 + 4 x^{3} - 2 x\)

\(P \left(\right. x \left.\right) = 6 x^{3} - 2 x^{2} + 3 x - 2\) \(Q \left(\right. x \left.\right) = - 2 x^{3} + 3 x^{2} - x + 4\) \(R \left(\right. x \left.\right) = 4 x^{3} - 2 x + 1\)

\(P \left(\right. x \left.\right) + Q \left(\right. x \left.\right)\)

\(P \left(\right. x \left.\right) + Q \left(\right. x \left.\right) = \left(\right. 6 x^{3} - 2 x^{3} \left.\right) + \left(\right. - 2 x^{2} + 3 x^{2} \left.\right) + \left(\right. 3 x - x \left.\right) + \left(\right. - 2 + 4 \left.\right)\) \(= 4 x^{3} + x^{2} + 2 x + 2\)

Trừ \(R \left(\right. x \left.\right)\)

\(\left(\right. P \left(\right. x \left.\right) + Q \left(\right. x \left.\right) \left.\right) - R \left(\right. x \left.\right) = \left(\right. 4 x^{3} + x^{2} + 2 x + 2 \left.\right) - \left(\right. 4 x^{3} - 2 x + 1 \left.\right)\)

Áp dụng dấu trừ:

\(= 4 x^{3} - 4 x^{3} + x^{2} + 2 x + 2 + 2 x - 1\) \(= 0 x^{3} + x^{2} + 4 x + 1\)

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