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

Toán Lớp 8: BÀI 1 TÍNH a) x – 2y^2 b)2x + 3y^2 c) ( 2x – y ) . (4x^2 +2 xy + y^2) d) x – 2 . x^2 +2x +4 e) 2x – 1^3 f) ( 7-x). ( 7+x) CÁC BẠN ƠI GI

Toán Lớp 8: BÀI 1 TÍNH
a) x – 2y^2
b)2x + 3y^2
c) ( 2x – y ) . (4x^2 +2 xy + y^2)
d) x – 2 . x^2 +2x +4
e) 2x – 1^3
f) ( 7-x). ( 7+x)
CÁC BẠN ƠI GIÚP MÌNH NHANH NHÉ MÌNH CẦN GẤP LẮM

Comments ( 1 )

  1. Giải đáp:
     $a) (x-2y)²$
    $= x²-2.x.2y+(2y)²$
    $= x²-4xy+4y²$
    $b)  (2x+3y)²$
    $= (2x)²+2.2x.3y+(3y)²$
    $= 4x²+12xy+9y²$
    $c) (2x-y).(4x²+2xy+y²)$
    $= (2x)³-y³$
    $= 8x³-y³$
    $d) (x-2).(x²+2x+4)$
    $= (x-2).(x²+x.2+2²)$
    $= x³-2³$
    $= x³-8$
    $e) (2x-1)³$
    $= (2x)³-3.(2x)².1+3.2x.1²-1³$
    $= 8x³-12x²+6x-1$
    $f) (7-x).(7+x)$
    $= 7²-x²$
    $= 49-x²$

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

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