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Toán Lớp 8: Rút gọn các biểu thức sau. a) (2x + 1)2 + (2x – 1)2 – 2(1 + 2x)(2x – 1) b) (x – 1)3 – (x + 2)(x2 – 2x + 4) + 3(x – 1)(x + 1)

Home/ Toán Lớp 8: Rút gọn các biểu thức sau. a) (2x + 1)2 + (2x – 1)2 – 2(1 + 2x)(2x – 1) b) (x – 1)3 – (x + 2)(x2 – 2x + 4) + 3(x – 1)(x + 1)

Toán Lớp 8: Rút gọn các biểu thức sau. a) (2x + 1)2 + (2x – 1)2 – 2(1 + 2x)(2x – 1) b) (x – 1)3 – (x + 2)(x2 – 2x + 4) + 3(x – 1)(x + 1)

Hồng Tháng Mười Hai 28, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Rút gọn các biểu thức sau.
a) (2x + 1)2 + (2x – 1)2 – 2(1 + 2x)(2x – 1)
b) (x – 1)3 – (x + 2)(x2 – 2x + 4) + 3(x – 1)(x + 1)

Comments ( 2 )

quynhthanhnhu
28 Tháng Mười Hai, 2022 at 11:51 sáng

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$a)$

$\left(2x+1\right)\cdot \:2+\left(2x-1\right)\cdot \:2-2\left(1+2x\right)\left(2x-1\right)$

$=2\left(2x+1\right)+2\left(2x-1\right)-2\left(1+2x\right)\left(2x-1\right)$

$=4x+2+2\left(2x-1\right)-2\left(1+2x\right)\left(2x-1\right)$

$=4x+2+4x-2-2\left(1+2x\right)\left(2x-1\right)$

$=4x+2+4x-2-8x^2+2$

$=-8x^2+4x+4x+2+2-2$

$=-8x^2+4x+4x+2$

$=-8x^2+8x+2$

$b)$

$\left(x-1\right).3-\left(x+2\right)\left(x^2-2x+4\right)+3\left(x-1\right)\left(x+1\right)$

$=3\left(x-1\right)-\left(x+2\right)\left(x^2-2x+4\right)+3\left(x-1\right)\left(x+1\right)$

$=3x-3-\left(x+2\right)\left(x^2-2x+4\right)+3\left(x-1\right)\left(x+1\right)$

$=3x-3-x^3-8+3\left(x-1\right)\left(x+1\right)$

$=3x-3-x^3-8+3x^2-3$

$=-x^3+3x^2+3x-3-3-8$

$=-x^3+3x^2+3x-14$
lanthuhoa
28 Tháng Mười Hai, 2022 at 11:51 sáng

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Bạn tham khảo

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