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

Toán Lớp 8: `a.x^2 + 6x – 9y^2 + 9` `b.x^3+2x^2+x` giúp ẹ

Toán Lớp 8: a.x^2 + 6x – 9y^2 + 9
b.x^3+2x^2+x
giúp ẹ

Comments ( 2 )

  1. $a.$ $x^2+6x-9y^2+9$
    $=\left(x+3\right)^2-9y^2$
    $=\left(x+3\right)^2-\left(3y\right)^2$
    $=\left(\left(x+3\right)+3y\right)\left(\left(x+3\right)-3y\right)$
    $=\left(x+3+3y\right)\left(x+3-3y\right)$
    $b.$ $x^3+2x^2+x$
    $=x\left(x^2+2x+1\right)$
    $=x\left(x+1\right)\left(x+1\right)$
    $=x\left(x+1\right)^2$

  2. Giải đáp:
     #Clickbim 
    a) x² + 6x – 9y² + 9
    = (x² + 6x + 9) – 9y²
    = (x² + 2.3x + 3²) – (3y)²
    = (x+3)² – (3y)²
    = (x+3-3y)(x+3+3y)
    -> HĐT (1) : (A+B)² = A² +2AB + B²
    -> HĐT (3) : A² – B² = (A-B)(A+B)
    b) x³ + 2x² + x
    =x(x² + 2x + 1)
    =x(x² + 2.1x +1²)
    =x(x+1) 
    ->HĐT(1) : (A+B)² = A² + 2AB + B²
    Lời giải và giải thích chi tiết:
     

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