giúp mình với huhu

\(=\dfrac{12\left(194+437+369\right)}{\dfrac{62\cdot13}{2}+26\cdot5}=\dfrac{12000}{533}\)

32 . 57 + 75 . 68 + 18 . 32

= 1824 + 5100 + 576

= 7500

tính hợp lí  

\(=\left(32\cdot57+18\cdot32\right)+75\cdot68\\ =32\cdot\left(57+18\right)+75\cdot68\\ =32\cdot75+75\cdot68\\ =75\cdot\left(32+68\right)=75\cdot100=7500\)

32.57+75.68+18.32 

= 32. (57+18) + 75.68 

= 32. 75 + 75. 68

= (32+68) .75

= 100 .75 

= 7500 

\(\Leftrightarrow\left(x-2021\right)\left(x-5\right)-\left(x-2021\right)=0\\ \Leftrightarrow\left(x-2021\right)\left(x-6\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2021\\x=6\end{matrix}\right.\)

57 x 0,1 x 100 x ( 2,5 x 4 - 10) = ( 2,5 x 4 - 10) x 57 x 100 x 0,1 

                                                = 0 x 57 x 0,1 x 100

                                                =   0

TL:

57 x 0,1 x 100 x ( 2,5 x 4 - 10)

=57 x 0,1 x100 x(10-10)

=57x0,1x100x0

= 0 

Học tốt

a: \(-177-\left\lbrack89+\left(-177\right)+75\right\rbrack-\left(-25\right)\)

=-177-[89-177+75]+25

=-177-89+177-75+25

=-89-50

=-139

b: \(2\cdot\left\lbrack16+\left(-12\right)-5\right\rbrack+\left(-32\right)-\left(-10\right)\)

\(=2\cdot\left\lbrack16-17\right\rbrack-32+10\)

=2*(-1)-32+10

=-34+10

=-24

c: \(56\cdot53-\left\lbrack57+\left(-75\right)-\left(-9\right)\cdot2\right\rbrack\)

=2968-[57-75+18]

=2968

d: \(16\cdot\left(-45\right)+16\cdot34-\left(-16\right)\cdot\left(-89\right)\)

\(=16\left(-45+34\right)-16\cdot89\)

\(=16\left(-11-89\right)=16\cdot\left(-100\right)=-1600\)

e: \(77\cdot18-\left(-77\right)\cdot60+\left(-77\right)\cdot\left(-22\right)\)

\(=77\cdot18+77\cdot60+77\cdot22\)

\(=77\left(18+60+22\right)=77\cdot100=7700\)

Sửa đề: 1/2*1/3+1/3*1/4+...+1/19*1/20

=1/2-1/3+1/3-1/4+...+1/19-1/20

=1/2-1/20=10/20-1/20=9/20