Giải Bài 19 trang 17 sách bài tập toán 7 tập 1 - Cánh diều

Đề bài

Tính:

a) \({2^5}\);                            

b) \({( - {\rm{ }}5)^3}\);    c) \({(0,4)^3}\);                 

d) \({( - {\rm{ 0,4)}}^3}\);

e) \({\left( {\dfrac{1}{2}} \right)^5}\);                           

g) \({\left( {\dfrac{{ - 1}}{3}} \right)^4}\);         

h) \({(21,5)^0}\);                        

i) \({\left( {3\dfrac{1}{2}} \right)^2}\).

Lời giải chi tiết

a) \({2^5} = 2.2.2.2.2 = 32\);                                           

b) \({( - {\rm{ }}5)^3} = ( - {\rm{ }}5).( - {\rm{ }}5).( - {\rm{ }}5) =  - 125\);          

c) \({(0,4)^3} = (0,4).(0,4).(0,4) = 0,064\);                     

d) \({( - {\rm{ 0,4)}}^3} = ( - {\rm{ 0,4}}).( - {\rm{ 0,4}}).( - {\rm{ 0,4}}) =  - 0,064\);

e) \({\left( {\dfrac{1}{2}} \right)^5} = \left( {\dfrac{1}{2}} \right).\left( {\dfrac{1}{2}} \right).\left( {\dfrac{1}{2}} \right).\left( {\dfrac{1}{2}} \right).\left( {\dfrac{1}{2}} \right) = \dfrac{1}{{32}}\);       

g) \({\left( {\dfrac{{ - 1}}{3}} \right)^4} = \left( {\dfrac{{ - 1}}{3}} \right).\left( {\dfrac{{ - 1}}{3}} \right).\left( {\dfrac{{ - 1}}{3}} \right).\left( {\dfrac{{ - 1}}{3}} \right) = \dfrac{1}{{81}}\);       

h) \({(21,5)^0} = 1\);                                                        

i) \({\left( {3\dfrac{1}{2}} \right)^2} = {\left( {\dfrac{7}{2}} \right)^2} = \left( {\dfrac{7}{2}} \right).\left( {\dfrac{7}{2}} \right) = \dfrac{{49}}{4}\).