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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: 1 tính (-8x^3y + 2y^4)(3xy^3 – 2x^4 + 7y) (2x -1)(3x + 2)(3 – x) 3x(2x + 5) + (6x – 1)(2 – x)+2 x^2+(3x + 1)(5x – 3) – (1 – 4x)^2 2 tí

Home/ Toán Lớp 8: 1 tính (-8x^3y + 2y^4)(3xy^3 – 2x^4 + 7y) (2x -1)(3x + 2)(3 – x) 3x(2x + 5) + (6x – 1)(2 – x)+2 x^2+(3x + 1)(5x – 3) – (1 – 4x)^2 2 tí

Toán Lớp 8: 1 tính (-8x^3y + 2y^4)(3xy^3 – 2x^4 + 7y) (2x -1)(3x + 2)(3 – x) 3x(2x + 5) + (6x – 1)(2 – x)+2 x^2+(3x + 1)(5x – 3) – (1 – 4x)^2 2 tí

Tháng Năm 1, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: 1 tính
(-8x^3y + 2y^4)(3xy^3 – 2x^4 + 7y)
(2x -1)(3x + 2)(3 – x)
3x(2x + 5) + (6x – 1)(2 – x)+2
x^2+(3x + 1)(5x – 3) – (1 – 4x)^2
2 tính
a, (x – 2y)^2
b, (2x^2 + 3)^2
c, (x – 2)(x^2 + 2x + 4)
d, ( 2x – 1)^3
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Comments ( 1 )

  1. lyly98
    lyly98
    1 Tháng Năm, 2022 at 1:57 sáng
    Reply
    Giải đáp:
    $1):$
     $a) (-8x³y+2y^4).(3xy^3-2x^4+7y)$
    $= (-8x³y).(3xy³-2x^4+7y)+2y^4.(3xy³-2x^4+7y)$
    $= -24x^4y^4+16x^7y-56x³y²+8xy^7-4x^4y^4+28y^5$
    $= [(-24x^4y^4)+(-4x^4y^4)]+16x^7y-56x³y²+8xy^7+28y^5$
    $= -28x^4y^4+16x^7y-56x³y²+8xy^7+28y^5$
    $b) (2x-1).(3x+2).(3-x)$
    $= (6x²+4x-3x-2).(3-x)$
    $= (6x²+x-2).(3-x)$
    $= 3.(6x²+x-2)-(6x²+x-2).x$
    $= 18x²+3x-6-6x³-x²+2x$
    $= (18x²-x²)-6x³+(3x+2x)-6$
    $= -6x^3+17x²+5x-6$
    $2):$
    $a) (x-2y)^2$
    $= x²-2.x.2y+(2y)²$
    $= x²-4xy+4y²$
    $b) (2x²+3)²$
    $= (2x²)²+2.2x².3+3²$
    $= 4x^4+12x²+9$
    $c) (x-2).(x^2+2x+4)$
    $= (x-2).(x²+x.2+2²)$
    $= x³-2³$
    $=x³-8$
    $d) (2x-1)³$
    $= (2x)³-3.(2x)².1+3.2x.1^2-1³$
    $= 8x³-12x²+6x-1$

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222-9+11+12:2*14+14 = ? ( )

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