\(\times+\left(\times+1\right)+\cdot\cdot\cdot+\left(\times+10\right)=660\)

\(\Rightarrow11\times+\left(1+2+\cdot\cdot\cdot+10\right)=660\)

\(\Rightarrow11\times+55=660\)

\(\Rightarrow11\times=660-55\)

\(\Rightarrow11\times=605\)

\(\Rightarrow\times=55\)

a) 46 874 – x = 1465

x = 46 874 – 1465

x = 45409

b) x - 1489 = 74 660

x = 74 660+1489

x = 76149

Sửa đề: \(\frac{1}{11\times16}+\frac{1}{16\times21}+\cdots+\frac{1}{x\times\left(x+5\right)}=\frac{1}{660}\)

=>\(\frac{5}{11\times16}+\frac{5}{16\times21}+\cdots+\frac{5}{x\times\left(x+5\right)}=\frac{5}{660}=\frac{1}{132}\)

=>\(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\cdots+\frac{1}{x}-\frac{1}{x+5}=\frac{1}{132}\)

=>\(\frac{1}{11}-\frac{1}{x+5}=\frac{1}{132}\)

=>\(\frac{1}{x+5}=\frac{1}{11}-\frac{1}{132}=\frac{12}{132}-\frac{1}{132}=\frac{11}{132}=\frac{1}{12}\)

=>x+5=12

=>x=7

y x 16 - y x 5 -y =550

y x (16-5-1)=550

y x 10=550

y=550:10

y=55

=> x - 750 + 100 -550 = 450

=> x-750 + 100=1000

=> x - 750=900

=> x=1650

có x-750+100-550=900:2

=) x-1200=450

x=450+1200

x=1650

X *  85 = 340 

X         = 340 : 85 

X        = 4 

^^ Học tốt nhé ! 

4 k nha

a.

806 660 000

b.

3 005 080

a) 806 660 000

b) 3 005 080

x= 350+200

x= 550

x= 400 -340

x= 60

TRỊNH ANH TUẤN

200 - x = 350

x           = 350 - 200

x           = 150

340 + x = 400

x           = 400 - 340

x           = 60

a

ảm ơn bn  nha