0,006dam² = 60 dm².

0,07m² = 700 cm².

0,67m² = 67 dm².

1m² = 0,01 dam².

1m² = 0,000001 km².

1 tấn 20g = 1000,02 kg.

0,006dam²= 60 dm²

0,07m² = 700 cm²

0,67m² = 67 dm²

1m² = 0,01 dam²

1m² = 0,000001 km².

1 tấn 20g = 1000,02 kg

a: Ta có: \(A=2+2^2+2^3+\cdots+2^{2025}\)

=>\(2A=2^2+2^3+2^4+\cdots+2^{2026}\)

=>\(2A-A=2^2+2^3+2^4+\cdots+2^{2026}-2-2^2-\cdots-2^{2025}\)

=>\(A=2^{2026}-2\)

b:Sửa đề: \(B=1+5+5^2+\cdots+5^{150}\)

=>\(5B=5+5^2+5^3+\cdots+5^{151}\)

=>\(5B-B=5+5^2+5^3+\cdots+5^{151}-1-5-5^2-\cdots-5^{150}\)

=>\(4B=5^{151}-1\)

=>\(B=\frac{5^{151}-1}{4}\)

c: Ta có: \(C=3+3^2+3^3+\ldots+3^{1000}\)

=>\(3C=3^2+3^3+3^4+\cdots+3^{1001}\)

=>\(3C-C=3^2+3^3+\cdots+3^{1001}-3-3^2-\cdots-3^{1000}\)

=>\(2C=3^{1001}-3\)

=>\(C=\frac{3^{1001}-3}{2}\)

Ta có: 3636:(12x−91)=36

12x–91=3636:36

12x–91=101

12x=101+91

12x=192

x=192:12

x=16

Vậy x=16

440 + 2. (125 – x) = 546

2. (125 - x)=546 - 440

2. (125 - x)=106

125 - x=106 : 2

125 - x=53

x=125-53

x=72

Đề mk ko hiểu gì cả 

sao ko hiểu

a: \(3636:\left(12\cdot x-91\right)=36\)

=>\(12x-91=\frac{3636}{36}=101\)

=>12x=91+101=192

=>\(x=\frac{192}{12}=16\)

b: \(446+2\cdot\left(125-x\right)=546\)

=>\(2\left(125-x\right)=546-446=100\)

=>125-x=50

=>x=125-50=75

c: \(\left(x-36\right):18=10+2\)

=>\(\left(x-36\right):18=12\)

=>\(x-36=18\cdot12=216\)

=>x=216+36=252

BÀI 1:

\(N=\frac{2}{2.5}+\frac{2}{5.8}+...+\frac{2}{17.20}\)

\(N=2.\left(\frac{1}{2.5}+\frac{1}{5.8}+...+\frac{1}{17.20}\right)\)

\(N=2.\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{17}-\frac{1}{20}\right)\)

\(N=2.\left(\frac{1}{2}-\frac{1}{20}\right)\)

\(N=2.\frac{9}{20}\)

\(N=\frac{9}{10}\)

BÀI 2:

\(C=1.2+2.3+3.4+...+99.100\)

\(\Rightarrow3B=1.2.3+2.3.3+3.4.3+...+99.100.3\)

\(3B=1.2\left(3-0\right)+2.3.\left(4-1\right)+3.4.\left(5-2\right)+...+99.100.\left(101-98\right)\)

\(3B=1.2.3+2.3.4-1.2.3+3.4.5-2.3.4+...+99.100.101-98.99.100\)

\(3B=\left(1.2.3+2.3.4+3.4.5+...+99.100.101\right)-\left(1.2.3+2.3.4+...+98.99.100\right)\)

\(3B=99.100.101\)

\(3B=999900\)

\(\Rightarrow B=999900:3\)

\(B=333300\)

CHÚC BN HỌC TỐT!!!!

Thanks CÔNG CHÚA ÔRI vì đã giúp mk

1+2+3+...+x = (1 + x) * x / 2 = 666

(1 + x) * x = 666 * 2 = 1332

1332 / x - 1 = x <=> x * (x + 1) = 1332

=> x = 36

\(\left(x+2\right)^2=3\)

=>\(\left[\begin{array}{l}x+2=\sqrt3\\ x+2=-\sqrt3\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\sqrt3-2\\ x=-\sqrt3-2\end{array}\right.\)

3 nhé bạn; 126 có 3 ước nguyên tố là 2;3;7

Mik cx hoc lop 6 nek.