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Câu 10: \(\left(x-2\right)\left(x^2+2x+4\right)=\left(2-2\right)\left(2^2+2\cdot2+4\right)=0\)
=>Chọn A
Câu 9: \(\left(3x-5\right)\left(2x+11\right)=\left(3\cdot0-5\right)\left(2\cdot0+11\right)=-5\cdot11=-55\)
=>Chọn C
Câu 8: \(\left(3x^2+3\right)\cdot\left(-\dfrac{1}{3}x\right)=-\dfrac{1}{3}x\cdot3x^2-\dfrac{1}{3}x\cdot3=-x^3-x\)
=>Chọn B
Câu 7: \(\left(2x-3\right)\left(3x+7\right)=6x^2+14x-9x-21=6x^2+5x-21\)
=>Không có câu nào đúng
Câu 6: \(\left(2x-1\right)\left(2x+1\right)=\left(2x\right)^2-1^2=4x^2-1\)
=>Chọn B
Câu 5: \(\left(x-1\right)\left(x+3\right)=x^2+3x-x-3=x^2+2x-3\)
=>Chọn A
Câu 4: \(\left(x+1\right)\left(x-2\right)=\left(0+1\right)\left(0-2\right)=1\cdot\left(-2\right)=-2\)
=>Chọn D
Câu 3: \(\left(x-3\right)\left(x-4\right)=x^2-4x-3x+12=x^2-7x+12\)
=>Chọn C
Câu 2: x(x2-2x+1)=x3-2x2+x
=>Chọn B
Câu 1: \(\left(3x+5\right)\left(2x-11\right)=6x^2-33x+10x-55\)
\(=6x^2-23x-55\)
=>Chọn D
