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

Toán Lớp 8: 1.(4-x)^2 2.(2+x)^2 3.(x-1/4)^2 4.(x+1/2)^2 5.x^2-4 6.x^2-9y^2 7.x^2-1

Toán Lớp 8: 1.(4-x)^2
2.(2+x)^2
3.(x-1/4)^2
4.(x+1/2)^2
5.x^2-4
6.x^2-9y^2
7.x^2-1

Comments ( 2 )

  1. 1)(4-x)²=4²-2.4.x+x²=16-8x+x²
    2)(2+x)²=2²+2.2.x+x²=4+4x+x²
    3)(x-1/4)^2=x²-2.x. 1/4+(1/4)^2=x²-1/2x+1/16
    4)(x+1/2)^2=x²+2.x. 1/2+(1/2)^2=x²+x+1/4
    5)x²-4=x²-2²=(x+2)(x-2)
    6)x²-9y²=x²-(3y)²=(x+3y)(x-3y)
    7)x²-1=x²-1²=(x+1)(x-1)

  2. Giải đáp:
    Câu 1 : (4 – x)^2 = x^2 – 8x + 16 
    Câu 2 : (2 + x)^2 = x^2 + 4x + 4 
    Câu 3 : (x – 1/4)^2 = (4x^2 – 2x + 1/4)/4
    Câu 4 : (x + 1/2)^2 = (2x^2 + 2x + 1/2)/2 
    Câu 5 : x^2 – 4 = x^2 – 2^2 = (x + 2)(x – 2) 
    Câu 6 : x^2 – 9y^2 = x^2 – (3y)^2 = (x – 3y)(x + 3y) 
    Câu 7 : x^2 – 1 = x^2 – 1^2 = (x – 1)(x + 1) 
    Lời giải và giải thích chi tiết:
     

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