a,\(\dfrac{x}{3}=\dfrac{y}{4}\)va x+y= 28          b, \(\dfrac{x}{9}=\dfrac{4}{x}\)

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viet cac cong thuc sau day bang cac ki hieu trong Exel

a, = 16 - 20 x 4      b, = ( 16 + 20 ) x 4      c, = (20 - 16 )⁴      d, = 500 ( 1+1/100)¹²

a, |3x -1| - 5 = 2          b, 9 ngu x :  3 ngu x = 81 

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