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

Toán Lớp 8: A.RÚT GỌN BIỂU THỨC SAU: 1.(x+1).(x ²-x+1)-(x-1).(x ²+xy) 2.(x-1 ) ³ – (x+1) ³ +6(x-1). (x+1) 3.(x+5) ² – (x-5) ² -20x + 2 4.(2x +6) .

Home/ Toán Lớp 8: A.RÚT GỌN BIỂU THỨC SAU: 1.(x+1).(x ²-x+1)-(x-1).(x ²+xy) 2.(x-1 ) ³ – (x+1) ³ +6(x-1). (x+1) 3.(x+5) ² – (x-5) ² -20x + 2 4.(2x +6) .

Toán Lớp 8: A.RÚT GỌN BIỂU THỨC SAU: 1.(x+1).(x ²-x+1)-(x-1).(x ²+xy) 2.(x-1 ) ³ – (x+1) ³ +6(x-1). (x+1) 3.(x+5) ² – (x-5) ² -20x + 2 4.(2x +6) .

Tháng Hai 9, 2023 Toán học 2 Comments 0 views

Toán Lớp 8: A.RÚT GỌN BIỂU THỨC SAU:
1.(x+1).(x ²-x+1)-(x-1).(x ²+xy)
2.(x-1 ) ³ – (x+1) ³ +6(x-1). (x+1)
3.(x+5) ² – (x-5) ² -20x + 2
4.(2x +6) . (4x ² -12x +36) -8x +5

Comments ( 2 )

  1. dananhthumai
    dananhthumai
    9 Tháng Hai, 2023 at 8:28 sáng
    Reply
    1)(x+1)(x²-x+1)-(x-1)(x²+xy)
    =x³+1-(x³+x²y-x²-xy)
    =x³+1-x³-x²y+x²+xy
    =(x³-x³)+x²-x²y+xy+1
    =x²-x²y+xy+1
    2)(x-1)³-(x+1)³+6(x-1)(x+1)
    =x³-3x²+3x-1-(x²+3x²+3x+1)+6(x²-1)
    =x³-3x²+3x-1-x³-3x²-3x-1+6x²-6
    =(x³-x³)+(-3x²-3x²+6x²)+(3x-3x)+(-1-1-6)
    =-8
    3)(x+5)²-(x-5)²-20x+2
    =x²+10x+25-(x²-10x+25)-20x+2
    =x²+10x+25-x²+10x-25-20x+2
    =(x²-x²)+(10x+10x-20x)+(25-25+2)
    =2
    4)(2x+6)(4x²-12x+36)-8x+5
    =(2x+6)[(2x)²-2x.6+6²]-8x+5
    =(2x)³+6³-8x+5
    =8x³+216-8x+5
    =8x³-8x+221
     

  2. thudan
    thudan
    9 Tháng Hai, 2023 at 8:28 sáng
    Reply
    Giải đáp:
     
    Lời giải và giải thích chi tiết:
    1.(x+1).(x ²-x+1)-(x-1).(x ²+xy)
    ⇔ x³-x²+x+x²-x+1-(x³+x²y-x²-xy)
    ⇔ x³-x²+x+x²-x+1-x³-x²y+x²+xy
    ⇔x²-x²y+xy+1
    2.(x-1 ) ³ – (x+1) ³ +6(x-1). (x+1)
    ⇔ x³-3x²+3x-1-( x³+3x²+3x+1)+6.(x²-1)
    ⇔x³-3x²+3x-1-x³-3x²-3x+1+6x²-6
    ⇔-8
    3.(x+5) ² – (x-5) ² -20x + 2
    ⇔ x²+10x+25 – (x²-10x+25)-20x+2
    ⇔x²+10x+25 -x²+10x-25-20x+2
    ⇔2
    4.(2x +6) . (4x ² -12x +36) -8x +5
    ⇔(2x)³+6³-8x+5
    ⇔8x³+216-8x+5
    ⇔8x³-8x+221
    chúc bạn học tốt !!

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

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