Bài 1 : thực hiện phép tính
a,25 - [49 - (2³ . 17 - 2³ .14)]
=25 - [49-(2³.(17-14))]
=25-(49-(8.3))
=25-(49-24)
=25-25
=0
b,|-45|+ |-15|: 3 + |10|.5
= 45+15:3+10.5
=45+5+50
=100
c, $\frac{3^{2}}{1.4}$ + $\frac{3^{2}}{4.7}$ +$\frac{3^{2}}{7.10}$ + $\frac{3^{2}}{10.13}$ + $\frac{3^{2}}{13.16}$
=$\frac{9}{1.4}$+$\frac{9}{4.7}$ + $\frac{9}{7.10}$ +$\frac{9}{10.13}$ + $\frac{9}{13.16}$
=3.($\frac{9}{1.4}$+$\frac{9}{4.7}$ + $\frac{9}{7.10}$ +$\frac{9}{10.13}$ + $\frac{9}{13.16}$)
=3.($\frac{1}{1}$-$\frac{1}{4}$ + $\frac{1}{4}$ -$\frac{1}{7}$ + $\frac{1}{7}$ -$\frac{1}{10}$+$\frac{1}{10}$ - $\frac{1}{13}$ +$\frac{1}{13}$ - $\frac{1}{16}$)
=3.($\frac{1}{1}$-$\frac{1}{16}$)
=3.$\frac{15}{16}$
=$\frac{45}{16}$
BẠN NHỚ CHO MÌNH CTLHN NHÉ!!!!