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

Toán Lớp 8: 1.Tính a,x.(2x+1) ²- x ². (x+2)+x ³-x+3 b,(x-1).(x+1).(x-4)-x ³-4 c,(x+y+z+t).(x+y-z-t)-x ²-y ²+z ²+t ²

Tháng Mười Một 30, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: 1.Tính
a,x.(2x+1) ²- x ². (x+2)+x ³-x+3
b,(x-1).(x+1).(x-4)-x ³-4
c,(x+y+z+t).(x+y-z-t)-x ²-y ²+z ²+t ²

Comments ( 2 )

  1. huyenmi76
    huyenmi76
    30 Tháng Mười Một, 2022 at 3:20 chiều
    Reply
    cho hay nhất và cảm ơn nhé

    toan-lop-8-1-tinh-a-2-1-2-3-b-1-1-4-4-c-y-z-t-y-z-t-y-z-t

  2. kimoanh34
    kimoanh34
    30 Tháng Mười Một, 2022 at 3:20 chiều
    Reply
    Giải đáp:
    a, x.(2x+1) ²- x ². (x+2)+x ³-x+3
    = x.(2x+1)(2x+1)-1x²(x+2)+x³+3
    = ????(2x(2????+1)+1(2x+1))−1????²(????+2)+????³−????+3
    =x(4x²+2x+1(2????+1))−1????²(????+2)+????³−????+3
    =????(4????²+2????+2????+1)−1????²(????+2)+????³−????+3
    =????(4????²+4x+1)−1????²(????+2)+????³−????+3
    =4x³+4x²+x−1????²(????+2)+????³−????+3
    =4????3+4????2+????−(x³+2x²)+????3−????+3
    =4????3+4????2+????−????3−2????2+????3−????+3
    =4????³+2x²+????−????3+????3−????+3
    =5x³+2????²+????−????³−????+3
    =5????³+2????²-x³+3
    =4x³+2x²+3
    b,(x-1).(x+1).(x-4)-x ³-4
    =x(x-4)(x+1)-1(x-4)(x+1)-1x³-4
    =(x+1).x²-4x(x+1)−1(????−4)(????+1)−1????³−4
    =x³+1x²−4????(????+1)−1(????−4)(????+1)−1????³−4
    =????³+????²−4????(????+1)−1(????−4)(????+1)−1????³−4
    =x³+x²-4x²-4x−1(????−4)(????+1)−1????³−4
    =????³−3????²−4????−1(????−4)(????+1)−1????³−4
    =????³−3????²−4????−(????(????+1)−4(????+1))−1????³−4
    =????³−3????²−4????−(????²+????−4(????+1))−1????³−4
    =????³−3????²−4????−(????²+????−4????−4)−1????³−4
    =????³−3????²−4????−(????²−3????−4)−1????³−4
    =????³−3????²−4????−????²+3????+4−1????³−4
    =????³−3????²−????−????²+4−1????³−4
    =????³−3????²−????²−????+4−1????³−4
    =????³−3????²−????²−????−????³
    =-4x²-x
    c,(x+y+z+t).(x+y-z-t)-
    =x²+xy-xz-xt+xy+y²-yz-yt+xz+yz-z²-zt+xt+yt-zt-t²-x ²-y ²+z ²+t ²
    =(x²+y²-z²-t²)-(x ²+y ²-z ²-t ²)+2xy-2zt
    =2xy-2zt

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

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