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

Toán Lớp 9: a) 3a(a+b)+2(a+b)² b) -2a(2a-1)-1(1-2a) c) 2(x-1)²-(x-1)³ d) 5(x-1)³-10(1-x)²

Tháng Mười Hai 28, 2022 Toán học 2 Comments 0 views

Toán Lớp 9: a) 3a(a+b)+2(a+b)²
b) -2a(2a-1)-1(1-2a)
c) 2(x-1)²-(x-1)³
d) 5(x-1)³-10(1-x)²

Comments ( 2 )

  1. ngocle44
    ngocle44
    28 Tháng Mười Hai, 2022 at 8:34 chiều
    Reply
    a) 3a(a+b) + 2(a+b)² 
    = (a+b)(3a+2a+2b)
    = (a+b)(5a+2b)
    b) -2a(2a-1)-1(1-2a)
    = -4a² + 2a – 1 + 2a
    = -4a² + 4a -1
    = -(4a²-4a+1)
    = -(2a-1)²
    c) 2(x-1)²-(x-1)³
    =(x-1)² (2-x+1)
    = (x-1)²(3-x)
    d) 5(x-1)³-10(1-x)² 
    = 5(x-1)³ – 10(x-1)²
    = (x-1)²[5(x-1)-10)
    = 5(x-1)²(x-3)
    = 5(x²-1)(x-1)
     

  2. lanngocha
    lanngocha
    28 Tháng Mười Hai, 2022 at 8:34 chiều
    Reply
    Hướng dẫn trả lời:
    a) 3acdot(a + b) + 2cdot(a + b)^2
    = [3a + 2cdot(a + b)]cdot(a + b)
    = (3a + 2a + 2b)cdot(a + b)
    = (5a + 2b)cdot(a + b)
    b) -2acdot(2a – 1) – 1cdot(1 – 2a)
    = -2acdot(2a – 1) – 1cdot-(2a – 1)
    = -2acdot(2a – 1) + 1cdot(2a – 1)
    = (-2a + 1)cdot(2a – 1)
    = -(2a – 1)cdot(2a – 1)
    = -(2a – 1)^2
    c) 2cdot(x – 1)^2 – (x – 1)^3
    = [2 – (x – 1)]cdot(x – 1)^2
    = (2 – x + 1)cdot(x – 1)^2
    = (- x + 3)cdot(x – 1)^2
    = – (x – 3)cdot(x – 1)^2
    d) 5cdot(x – 1)^3 – 10cdot(1 – x)^2
    = 5cdot(x – 1)^3 – 10cdot(x – 1)^2
    = [5cdot(x – 1) – 10]cdot(x – 1)^2
    = (5x – 5 – 10)cdot(x – 1)^2
    = (5x – 15)cdot(x – 1)^2
    = 5cdot(x – 3)cdot(x – 1)^2
    Giải đáp:
    a) = (5a + 2b)cdot(a + b)
    b) = – (2a – 1)^2
    c) = – (x – 3)cdot(x – 1)^2
    d) = 5cdot(x – 3)cdot(x – 1)^2

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

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