Question

quy đồng mẫu số rồi tính

a. 10/13 + 9/16                  7/90 + 123/270

b. 19/21 - 5/12                   90/100 - 25/40

Answer 1

a. 10/13 + 9/16         
=160/208+117/208
=277/208
7/90 + 123/270
=7/90+41/90
=48/90
=8/15

b. 19/21 - 5/12                 
=76/84-35/84
=41/84
 90/100 - 25/40
=9/10-25/40
=36/40-25/40
=11/40

Answer 2

a. 10/13 + 9/16         
=160/208+117/208
=277/208
7/90 + 123/270
=7/90+41/90
=48/90
=8/15

b. 19/21 - 5/12                 
=76/84-35/84
=41/84
 90/100 - 25/40
=9/10-25/40
=36/40-25/40
=11/40

Answer 3

a) \(\dfrac{10}{13}+\dfrac{9}{16}\)                         \(\dfrac{7}{90}+\dfrac{123}{270}\)

= \(\dfrac{160}{208}+\dfrac{117}{208}\)                   = \(\dfrac{7}{90}+\dfrac{41}{90}\)

= \(\dfrac{277}{208}\)                              = \(\dfrac{8}{15}\)

b) \(\dfrac{19}{21}-\dfrac{5}{12}\)                       \(\dfrac{90}{100}-\dfrac{25}{40}\)

= \(\dfrac{76}{84}-\dfrac{35}{84}\)                      = \(\dfrac{9}{10}-\dfrac{25}{40}\)

= \(\dfrac{41}{84}\)                               = \(\dfrac{36}{40}-\dfrac{25}{40}\)

                                      = \(\dfrac{11}{40}\)

Hok tốt 

Answer 4

hãy học rốt nhé