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

Toán Lớp 8: Rút gọn biểu thức sau: a) (x + 2) (x – 2) – (x – 3) (x + 1) b) (x + 2) ² – 2(x + 2) (x – 3) + (x – 3) ²

Toán Lớp 8: Rút gọn biểu thức sau:
a) (x + 2) (x – 2) – (x – 3) (x + 1)
b) (x + 2) ² – 2(x + 2) (x – 3) + (x – 3) ²

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    a)(x+2)(x-2)-(x-3)(x+1) 
    =(x^2-4)-(x^2-3x+x-3)
    =x^2-4-x^2+2x+3
    =2x-1
    b)(x+2)^2-2(x+2)(x-3)+(x-3)^2
    =[(x+2)-(x-3)]^2
    =(x+2-x+3)^2
    =5^2
    =25

  2. $a)(x + 2) (x – 2) – (x – 3) (x + 1)$
    $=x^2-2^2-(x^2+x-3x-3)$
    $=x^2-4-x^2-x+3x+3$
    $=2x-1$
    $b) (x + 2)^2 – 2(x + 2) (x – 3) + (x – 3)^2$
    $=[(x+2)-(x-3)]^2$
    $=(x+2-x+3)^2$
    $=5^2$
    $=25$
    $#thanhmaii2008$

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