\(A=\left(\dfrac{1}{49}-\dfrac{1}{2^2}\right)\left(\dfrac{1}{49}-\dfrac{1}{3^2}\right)\cdot...\cdot\left(\dfrac{1}{49}-\dfrac{1}{100^2}\right)\)

\(=\left(\dfrac{1}{49}-\dfrac{1}{7^2}\right)\left(\dfrac{1}{49}-\dfrac{1}{2^2}\right)\cdot...\cdot\left(\dfrac{1}{49}-\dfrac{1}{100^2}\right)\)

\(=\left(\dfrac{1}{49}-\dfrac{1}{49}\right)\left(\dfrac{1}{49}-\dfrac{1}{4}\right)\cdot...\cdot\left(\dfrac{1}{49}-\dfrac{1}{10000}\right)\)

=0

Tham khảo:

Câu 48: 

ai nhanh nhất mình sẽ tick ạ!

46 B

47 A

48 C

49 A

Câu 48: A

Câu 49: B

    \(\dfrac{2}{49}\) x 121 : \(\dfrac{22}{7}\)

= \(\dfrac{2}{49}\) x 121 x \(\dfrac{7}{22}\)

= \(\dfrac{2}{7\times7}\) \(\times\)\(\dfrac{11\times11\times7}{11\times2}\) 

= \(\dfrac{11}{7}\)

\(\dfrac{2}{49}\times121:\dfrac{22}{7}\)

\(=\dfrac{2\times121}{49}\times\dfrac{7}{22}\)

\(=\dfrac{2\times121\times7}{49\times22}\)

\(=\dfrac{2\times11\times11\times7}{7\times7\times22}\)

\(=\dfrac{22\times11}{7\times22}\)

\(=\dfrac{11}{7}\)

\(\dfrac{2}{49}\times121:\dfrac{22}{7}\)

\(=\dfrac{2\times121}{49}\times\dfrac{7}{22}\)

\(=\dfrac{2\times121\times7}{49\times22}\)

\(=\dfrac{11}{7}\)

= (-71) nha 

Chúc cậu học tốt:3 

d)5( x+4)=135-35

       x+4=100:5

       x    =20-4

      x     =16

d) 135 - 5 (x+4) = 35

5 (x+4) = 135 - 35

5 (x+4) = 100

(x+4) = 100 : 5

x + 4 = 20

x = 20 - 4

x = 16

e) 25 + 3 ( x - 8 ) = 106 

3  ( x - 8 ) = 106 - 25 

3  ( x - 8 ) = 81 

x - 8 = 81 : 3 

x - 8 = 27 

x = 27 + 8 

x = 35 

f) 2x – 49 = 5. 32

2x - 49 = 160

2x = 160 + 49

2x = 209

x = 209 : 2

x = 104,5

d)\(135-5\left(x+4\right)=35\)

⇔\(5\left(x+4\right)=100\)

⇔\(x+4=20\)

⇔\(x=16\)

e)\(25+3\left(x-8\right)=106\)

⇔\(3\left(x-8\right)=81\)

⇔\(x-8=27\)

⇔\(x=35\)

f)\(2x-49=5.32\)

⇔\(2x-49=160\)

⇔\(2x=209\)

⇔\(x=\dfrac{209}{2}\)

phiếu ôn tập 1 nha mình nhầm

bạn gửi đề đi mình ko học VNEN à!

\(\left(x-1\right)^2=49\)

\(\Leftrightarrow\orbr{\begin{cases}x-1=49\\x-1=-49\end{cases}\Leftrightarrow\orbr{\begin{cases}x=50\\x=-48\end{cases}}}\)

                              Đáp án là (8-1)^2=49

xin lỗi nhé. Mình làm sai rồi