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

Toán Lớp 8: Thu gọn biểu thức a, A=( 3 + 4 y)^2 + 2(3 + 4 y)( 3 – 4 y )+( 4 y + 3)^2 b, B=3(x – 1)^2 – (x + 1)^2 + 2(x – 3) (x + 3) – (2 x + 3)^2 c

Tháng Một 16, 2023 Toán học 1 Comment 0 views

Toán Lớp 8: Thu gọn biểu thức
a, A=( 3 + 4 y)^2 + 2(3 + 4 y)( 3 – 4 y )+( 4 y + 3)^2
b, B=3(x – 1)^2 – (x + 1)^2 + 2(x – 3) (x + 3) – (2 x + 3)^2
c, C=(x + 2)^3 + (2x – 1)^3 -18x -9(x^3-2)
d, D=(2x – 1)^3 – 6 x (2 x -1)^2 + 12 x^2( 2x – 1 ) – 8x^3
e, E=(x + y)^3 – (x – y)^3 – 2y (y^2 + 3x^2)
f, F=(x + y)^3 – (x^3+y^3) – 3xy (x+y)
* những hằng đẳng thức đáng nhớ.
giúp tui zới, pls

Comments ( 1 )

  1. truongthanhhung
    truongthanhhung
    16 Tháng Một, 2023 at 4:47 sáng
    Reply
    a)A=(3+4y)²+2(3+4y)(3-4y)+(4y+3)²
    =9+24y+16y²+2(9-16y²)+16y²+24y+9
    =9+24y+16y²+18-32y²+16y²+24y+9
    =(16y²-32y²+16y²)+(24y+24y)+(9+18+9)
    =48y+36
    b)B=3(x-1)²-(x+1)²+2(x-3)(x+3)-(2x+3)²
    =3(x²-2x+1)-(x²+2x+1)+2(x²-9)-(4x²+12x+9)
    =3x²-6x+3-x²-2x-1+2x²-18-4x²-12x-9
    =(3x²-x²+2x²-4x²)+(-6x-2x-12x)+(3-1-18-9)
    =-20x-25
    c)C=(x+2)³+(2x-1)³-18x-9(x³-2)
    =x³+6x²+12x+8+8x³-12x²+6x-1-18x-9x³+18
    =(x³+8x³-9x³)+(6x²-12x²)+(12x+6x-18x)+(8-1+18)
    =-6x²+25
    d)D=(2x-1)³-6x(2x-1)²+12x²(2x-1)-8x³
    =(2x-1)³-3.(2x-1)².2x+3.(2x-1).(2x)²-(2x)³
    =(2x-1-2x)³
    =(-1)³
    =-1
    e)E=(x+y)³-(x-y)³-2y(y²+3x²)
    =x³+3x²y+3xy²+y³-(x³-3x²y+3xy²-y³)-2y³-6x²y
    =x³+3x²y+3xy²+y³-x³+3x²y-3xy²+y³-2y³-6x²y
    =(x³-x³)+(3x²y+3x²y-6x²y)+(3xy²-3xy²)+(y³+y³-2y³)
    =0
    f)F=(x+y)³-(x³+y³)-3xy(x+y)
    =x³+3x²y+3xy²+y³-x³-y³-3x²y-3xy²
    =(x³-x³)+(3x²y-3x²y)+(3xy²-3xy²)+(y³-y³)
    =0

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

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