Tính giá trị biểu thức:
A= -11/23. 10/13+ 11/-13 : -3/23 – (-12/23)
B= (-5/6): (-10/3+ 9/4) – (-3/8): ( 8- 51/8)
C= (-3,2) . -15/64 + ( 0,8 – 14/5) : 11/3
D= 4/7. (8/-13) + 4/7. (-2/13) + 16/13. (-4/7)
Tính giá trị biểu thức: A= -11/23. 10/13+ 11/-13 : -3/23 – (-12/23) B= (-5/6): (-10/3+ 9/4) – (-3/8): ( 8- 51/8) C= (-3,2) . -15/64 + ( 0,8 – 14/5) :
By Hailey
`a) A = (-11)/23 . 10/13 + 11/(-13) : (-3)/23 – (-12)/23`
` = (-11)/23 . 10/13 + (-11)/13 . (-23)/3 + 12/23`
` = (-110)/299 + 253/39 + 12/23`
` = (-330)/897 + 5819/897 + 468/897`
` = 5957/897`
` = 259/39`
`b) B = (-5)/6 : (-10/3 + 9/4) – (-3/8) : (8 – 51/8)`
` = (-5)/6 : (-13)/12 – (-3/8) : 13/8`
` = (-5)/6 . (-12)/13 – (-3/8) . 8/13`
` = 10/13 + 3/13`
` = 1`
`c) C = (-3,2) . (-15)/64 + (0,8 – 14/5) : 11/3`
` = 3/4 +(-2) : 11/3`
` = 3/4 – 6/11`
` = 9/44`
`d) D = 4/7 . (8/-13) + 4/7 . (-2/13) + 16/13 . (-4/7)`
` = 4/7 . (-8)/13 + 4/7 . (-2)/13 – 4/7 . 16/13`
`= 4/7 . (-8/13 – 2/13 – 16/13)`
` = 4/7 . (-2)`
` = -8/7`
Đáp án:
`A = (-11)/23 × 10/13 + 11/(-13) ÷ (-3)/23 – (-12)/23`
`⇔ A = (-11)/23 × 10/13 + (-11)/13 × (-23)/3 + 12/23`
`⇔ A = (-110)/299 + 253/39 + 12/23`
`⇔ A = (-330)/897 + 5819/897 + 468/897`
`⇔ A = (-330 + 5819 + 468)/897`
`⇔ A = 259/39`
Vậy `A = 259/39`
$\\$
$\\$
`B = (-5)/6 ÷ ( (-10)/3 + 9/4) – (-3)/8 ÷ (8 – 51/8)`
`⇔ B = (-5)/6 ÷ (-13)/12 – (-3)/8 ÷ 13/8`
`⇔ B = (-5)/6 × (-12)/13 – (-3)/8 × 8/13`
`⇔ B = 10/13 – (-3)/13`
`⇔ B = (10 – (-3) )/13`
`⇔ B = 1`
Vậy `B=1`
$\\$
$\\$
`C= (-3,2) × (-15)/64 + (0,8 – 14/5) ÷ 11/3`
`⇔ C = (-16)/5 × (-15)/64 + (-2) ×3/11`
`⇔ C = 3/4 + (-6)/11`
`⇔ C = 33/44 + (-24)/44`
`⇔ C = (33 + (-24) )/44`
`⇔ C = 9/44`
Vậy `C = 9/44`
$\\$
$\\$
`D = 4/7 × 8/(-13) + 4/7 × (-2)/13 + 16/13 × (-4)/7`
`⇔ C = 4/7 × (-8)/13 + 3/7 × (-2)/13 + (-16)/13 × 4/7`
`⇔ C = 4/7 × [(-8)/13 + (-2)/13 + (-16)/13]`
`⇔ C = 4/7 × (-2)`
`⇔ C = (-8)/7`
Vậy `C = (-8)/7`