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

Toán Lớp 8: Rút gọn a. (x+y)² – (x-y)² b, $\frac{2x-3}{5}$ + $\frac{3x+3}{5}$ giúp mình với ạ, mình cảm ơn ^^

Toán Lớp 8: Rút gọn
a. (x+y)² – (x-y)²
b, $\frac{2x-3}{5}$ + $\frac{3x+3}{5}$
giúp mình với ạ, mình cảm ơn ^^

Comments ( 2 )

  1. a. (x + y)² – (x – y)²
    = (x² + 2xy + y²) – (x² – 2xy + y²)
    = x² + 2xy + y² – x² + 2xy – y²
    = 4xy
    b. $\frac{2x-3}{5}$ + $\frac{3x + 3}{5}$ = $\frac{2x – 3 + 3x + 3}{5}$ = $\frac{5x}{5}$ = x
     

  2. a,
    (x+y)^2-(x-y)^2
    =(x+y-x+y)(x+y+x-y)
    =2y.2x
    =4xy
    b,
    (2x-3)/5 + (3x+3)/5
    =(2x-3+3x+3)/5
    =(5x)/5
    =x

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