9 + 18 + 27 + 36 + 45 + 54 + 63 + 72 + 90 = 414

kết quả là :

   414 

      đs...

1 x 9 = 9

2 x 9 = 18

3 x 9 = 27

4 x 9 = 36

5 x 9 = 45

6 x 9 = 54

7 x 9 = 63 

8 x 9 =72

9 x 9 = 81

10 x 9 = 90

Câu hỏi là : 9 + 18 + 27 + 36 + 45 + 54 + 63 + 72 + 81 +90 =414

a. \(\dfrac{x}{5}=\dfrac{8}{10}\)

\(\Rightarrow10x=8.5\)

\(\Rightarrow10x=40\)

\(\Rightarrow x=\dfrac{40}{10}=4\)

b. \(\dfrac{9}{x}=\dfrac{90}{100}\)

\(\Rightarrow9.100=90x\)

\(\Rightarrow900=90x\)

\(\Rightarrow x=\dfrac{900}{90}=10\)

c. \(17+\dfrac{x}{35}=\dfrac{5}{7}\)

\(\Rightarrow\dfrac{595+x}{35}=\dfrac{25}{35}\)

\(\Rightarrow595+x=25\)

\(\Rightarrow x=25-595=-570\)

d. \(x:\dfrac{5}{27}=\dfrac{2}{9}\)

\(\Rightarrow\dfrac{27x:5}{27}=\dfrac{6}{27}\)

\(\Rightarrow27x:5=6\)

\(\Rightarrow27x=5.6\)

\(\Rightarrow27x=30\)

\(\Rightarrow x=\dfrac{30}{27}=\dfrac{10}{9}\approx1,11\)

90 + 90 = 180

2 x 2 = 4

9 x 9 = 81

8 x 8 = 64

200 x 1860 = 336 000

89 x 22 = 1958

88 x 11 = 968

1980 x 1980 + 1980 x 2980 = 9 820 800

20000 x 400 = 8 000 000

9960 x 2235 = 22 260 600

90 + 90 = 180

2 x 2 = 4

9 x 9 = 81

8 x 8 = 64

200 x 1860 = 372000

89 x 22 = 1958

88 x 11 = 968

1980 x 1980 + 1980 x 2980 = 9820800

20000 x 400 = 8000000

9960 x 2235 =22260600

k mik nha 

chúc bạn hok giỏi

90 + 90 = 180

2 x 2 = 4

9 x 9 = 81

8 x 8 = 64

200 x 1860 = 372000

89 x 22 =1958

88 x 11 =  968

1980 x 1980 + 1980 x 2980 = 9820800

20000 x 400 = 8000000

9960 x 2235 = 22260600

\(\left(x+1\right)+\left(x+2\right)+...+\left(x+9\right)=90\)

Ta có 9 SSH (từ 1 đến 9)

9.x+(1+2+3+...+9)=90

9x+(9+1).9:2=90

9x+45=90

9x=90-45=45

x=45:9

x=5

(x+1)+(x+2)+...+(x+9)=90

Ta có 9 SSH (từ 1 đến 9)

9.x+(1+2+3+...+9)=90

9x+(9+1).9:2=90

9x+45=90

9x=90-45=45

x=45:9

x=5

\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+9\right)=90\)

\(\Rightarrow\left(x+x+x+...+x\right)+\left(1+2+3+...+9\right)=90\)

\(\Rightarrow9x+45=90\)

\(\Rightarrow9x=90-45\)

\(\Rightarrow9x=45\Rightarrow x=5\)

help me pls