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

Toán Lớp 8: Bài 1. Phân tích các đa thức sau thành nhân tử: a/ 5xy^2 -10xyz + 5xz^2 b/ 3x-6y c/1 – 4x^2 d/ 8 – 27x^3 e/ x^3 + 8y^3 f/ x2 – 25 –

Tháng Ba 18, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Bài 1. Phân tích các đa thức sau thành nhân tử:
a/ 5xy^2 -10xyz + 5xz^2
b/ 3x-6y
c/1 – 4x^2
d/ 8 – 27x^3
e/ x^3 + 8y^3
f/ x2 – 25 – 2xy + y2
g/ x^2-4x+4-y^2
h/(x^2 + 1)^2 – 4x^2

Comments ( 2 )

  1. thanhthuythu
    thanhthuythu
    18 Tháng Ba, 2022 at 8:04 sáng
    Reply
    a, 5xy^2-10xyz+5xz^2
    5xy^2 – 10xyz + 5xz^2
    = 5x(y^2-2yz+z^2)
    = 5x(y-z)^2
    b, 3x – 6y
    = 3.x – 3.2y
    = 3(x – 2y)
    c, 1-4x^2
    =1 – 2^2x^2
    = (1 + 2x) .(1 – 2x)
    = (2x + 1).(1 – 2x) 
    d, 8- 27x^3
    = 2^3 – (3x)^3
    = ( 2-3x)(4 + 6x+ 9x^2)
    e, x^3 + 8y^3
    = x^3 + 2^3y^3
    = x^3 + (2y)^3
    = (x + 2y)(x^2 – x . 2y(2y)^2)
    = (x + 2y)(x^2 – 2xy + 4y^2)
    f, $x^2-25-2xy+y^2$
    $=\left(x^2-2xy+y^2\right)-25$
    $=\left(x-y\right)^2-5^2$
    $=\left(x-y-5\right)\left(x-y+5\right)$
    g, x^2 + 4x + 4 – y^2
    = (x + 2)^2 – y^2
    = (x + 2 – y)(x + 2 + y)
    h, (x^2+1)^2 – 4x^2
    =(x^2+1)^2 – (2x)^2
    =(x^2+1-2x)(x^2+1+2x)
    =(x^2-2x+1)(x^2+2x+1)
    =(x-1)^2(x+1)^2

  2. behocgioitoan
    behocgioitoan
    18 Tháng Ba, 2022 at 8:04 sáng
    Reply
    Giải đáp:
     $a) 5xy²-10xyz+5xz²$
    $= 5x.(y²-2yz+z²)$
    $= 5x.(y-z)²$
    $b) 3x-6y$
    $= 3.x-3.2y$
    $= 3.(x-2y)$
    $c) 1-4x²$
    $= 1²-(2x)²$
    $= (1-2x).(1+2x)$
    $d) 8-27x³$
    $= 2³-(3x)³$
    $= (2-3x).[2²+2.3x+(3x)²]$
    $= (2-3x).(4+6x+9x²)$
    $e) x³+8y³$
    $= x³+(2y)³$
    $= (x+2y).(x²-2xy+4y²)$
    $f) x²-25-2xy+y²$
    $= (x²-2xy+y²)-25$
    $= (x-y)²-5²$
    $= (x-y-5).(x-y+5)$
    $g) x²-4x+4-y²$
    $= (x-2)²-y²$
    $=(x-2-y).(x-2+y)$
    $h) (x²+1)²-4x²$
    $= (x²+1)²-(2x)²$
    $= (x²+1-2x).(x²+1+2x)$
    $= (x-1)².(x+1)²$
     

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

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