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

Toán Lớp 8: phân tích đa thức thành nhân tử 1, 9$(a+b)^{2}$ -4$(a-2b)^{2}$ 2, 36 x-$y^{2}$ -25.2x-$1^{2}$ 3,$x^{2}$ +10x +25 4, $x^{2}$ +8x +1

Toán Lớp 8: phân tích đa thức thành nhân tử
1, 9$(a+b)^{2}$ -4$(a-2b)^{2}$
2, 36 x-$y^{2}$ -25.2x-$1^{2}$
3,$x^{2}$ +10x +25
4, $x^{2}$ +8x +16
5, $x^{2}$ +6x +9

Comments ( 1 )

  1. #Sad
    1)
    9(a+b)^2-4(a-2b)^2
    = (3a+3b)^2-(2a-4b)^2
    = (3a+3b-2a+4b)(3a+3b+2a-4b)
    = (a+7b)(5a-b)
    2)
    36-y^2-2y-1
    = 36-(y^2+2y+1)
    = 6^2-(y+1)^2
    = (6-y-1)(6+y+1)
    = (5-y)(7+y)
    3)
    x^2+10x+25
    = x^2+2. 5. x. 5^2
    = (x+5)^2
    4)
    x^2+8x+16
    = x^2+2. 4. x+4^2
    = (x+4)^2
    5)
    x^2+6x+9
    = x^2+2. 3. x+3^2
    = (x+3)^2
     

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