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

Toán Lớp 7: 1) 5 (2x+3) ( x+2) -2 ( 5x-4) (x-1) 2) (10x+9) x- (5x-1) (2x+3) 3) 3 (2x-1) -5 (x-3)+6 ( 3x-4) 4) (3x-1) ( 2x+7) –(x+1) (6x-5) 5) (3x

Toán Lớp 7: 1) 5 (2x+3) ( x+2) -2 ( 5x-4) (x-1)
2) (10x+9) x- (5x-1) (2x+3)
3) 3 (2x-1) -5 (x-3)+6 ( 3x-4)
4) (3x-1) ( 2x+7) –(x+1) (6x-5)
5) (3x-5) (7-5x) + (5x+2) (3x-2)-2

Comments ( 2 )

  1. Giải đáp:
     1)53x+22
    2)-4x+3
    3)19x-12
    4)18x-2
    5)42x-41
    Lời giải và giải thích chi tiết:
     1)
    5(2x+3).(x+2)-2(5x-4).(x-1)
    =5.(2x^2+7x+6)-2.(5x^2-9x+4)
    =10x^2+35x+30-10x^2+18x-8
    =(10x^2-10x^2)+(35x+18x)+(30-8)
    =53x+22
    2)
    (10x+9).x-(5x-1).(2x+3)
    =10x^2+9x-(10x^2+13x-3)
    =10x^2+9x-10x^2-13x+3
    =(10x^2-10x^2)+(9x-13x)+3
    =-4x+3
    3)
    3.(2x-1)-5.(x-3)+6.(3x-4)
    =6x-3-5x+15+18x-24
    =(6x-5x+18x)+(-3+15-24)
    =19x-12
    4)
    (3x-1).(2x+7)-(x+1).(6x-5)
    =6x^2+19x-7-(6x^2+x-5)
    =6x^2+19x-7-6x^2-x+5
    =(6x^2-6x^2)+(19x-x)+(-7+5)
    =18x-2
    5)
    (3x-5).(7-5x)+(5x+2).(3x-2)-2
    =46x-15x^2-35+15x^2-4x-4-2
    =(-15x^2+15x^2)+(46x-4x)+(-35-4-2)
    =42x-41

  2. Giải đáp:
    1)53x+22
    2)-4x+3
    3)19x-12
    4)18x-2
    5)42x-41
    Lời giải và giải thích chi tiết:
    1)5(2x+3)(x+2)-2(5x-4)(x-1)
    =(10x+15)(x+2)-2(5x²-5x-4x+4)
    =10x²+20x+15x+30-10x²+10x+8x-8
    =(10x²-10x²)+(20x+15x+10x+8x)+(30-8)
    =53x+22
    2)(10x+9)x-(5x-1)(2x+3)
    =10x²+9x-(10x²+15x-2x-3)
    =10x²+9x-10x²-15x+2x+3
    =(10x²-10x²)+(9x-15x+2x)+3
    =-4x+3
    3)3(2x-1)-5(x-3)+6(3x-4)
    =6x-3-5x+15+18x-24
    =(6x-5x+18x)+(-3+15-24)
    =19x-12
    4)(3x-1)(2x+7)-(x+1)(6x-5)
    =6x²+21x-2x-7-(6x²-5x+6x-5)
    =6x²+21x-2x-7-6x²+5x-6x+5
    =(6x²-6x²)+(21x-2x+5x-6x)+(-7+5)
    =18x-2
    5)(3x-5)(7-5x)+(5x+2)(3x-2)-2
    =21x-15x²-35+25x+15x²-10x+6x-4-2
    =(-15x²+15x²)+(21x+25x-10x+6x)+(-35-4-2)
    =42x-41

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