Question

Tính bằng cách hợp lý:

A = (-5,85) + {[(+41,3)+(+5) + (+0,85))}

B = (-87,5) + {(+87,5) + [(+3,8) + (-0,8)]}

C = [(+9,5) + (-13)] + [(-5) + (8,5)]

Answer 1

A = (-5,85) + {[(+41,3)+(+5) + (+0,85))}

= {(-5,85) + [(+5) + (0,85)]} + (+ 41,3)

= {(-5,85) + (5,85)} + (+ 41,3)

= 0 + 41,3

= 41,3

B = (-87,5) + {(+87,5) + [(+3,8) + (-0,8)]}

= [(-87,5) + (+87,5)] + [(+3,8) + (-0,8)]

= 0 + 3 = 3

C = [(+9,5) + (-13)] + [(-5) + (8,5)]

= [(+9,5) + (+8,5)] + [(-5) + (-13)]

= 18 + (-18) = 0