a) 5 : 3/4 - 4 4/5 : 3/4

= 5 . 4/3 - 24/5 . 4/3

= (5 - 24/5) . 4/3

= 1/5 × 4/3

= 4/15

b) -3/5 . 2/7 + (-3/7) . 3/5 + (-3/7)

= (-3/7) . (2/5 + 3/5 + 1)

= (-3/7) . 2

= -6/7

c) [(-4 2/7) . 7/11 + 7/11 . (5 1/3)] . 5 - 5 2/3

= (-30/7 . 7/11 + 7/11 . 16/3) . 5 - 17/3

= (-30/11 + 112/33) . 5 - 17/3

= 2/3 . 5 - 17/3

= 10/3 - 17/3

= -7/3

d) 5/39 . [(7 4/5) . (1 2/3) + (8 1/3) . (7 4/5)]

= 5/39 . (39/5 . 5/3 + 25/3 . 39/5)

= 5/39 . 39/5 . (5/3 + 25/3)

= 1 . 10

= 10

= 

câu 1 x=-3 hoặc 3

x=2 hoặc -2

x thuộc rỗng

x thuộc rỗng

-3/4+3/4* (x-1/2)+1/6=-1

=0*(x-1/2)=-7/6

nên ko tìm đc x

P= 7x²-3xy³+4
P= 7.(-2)²-3.(-2).(-1/2)³+4
=7.4-3.(-2).(-1/8)+4
=28-(-6).(-1/8)+4
=28-3/4+4
=109/4+4
=125/4
kb đúng hay sai.

\(\dfrac{2}{20}-\dfrac{-3}{36}+\dfrac{4}{60}=\dfrac{1}{4}\)

=\(\dfrac{1}{4}\)

\(\dfrac{2}{20}-\left(-\dfrac{3}{36}\right)+\dfrac{4}{60}\\ =\dfrac{1}{10}+\dfrac{1}{12}+\dfrac{1}{15}\\ =\dfrac{6}{60}+\dfrac{5}{60}+\dfrac{4}{60}\\ =\dfrac{6+5+4}{60}\\ =\dfrac{15}{60}\\ =\dfrac{1}{4}\)

bằng 19/44 nhá

tớ tính mãi mới ra

.......................................

19/44

\(\dfrac{43}{44}\)