(\(x\) + 2)² + 2(\(x\) + 2)(\(x\) - 1) + (\(x\) - 1)² = 16

(\(x\) + 2 + \(x\) - 1)² = 16

[(\(x\) + \(x\)) + (2 - 1)]² = 16

[2\(x\) + 1]² = 16

\(\left[{}\begin{matrix}2x+1=4\\2x+1=-4\end{matrix}\right.\)

 \(\left[{}\begin{matrix}2x=4-1\\2x=-4-1\end{matrix}\right.\)

  \(\left[{}\begin{matrix}2x=3\\2x=-5\end{matrix}\right.\)

  \(\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\)

Vậy \(x\) \(\in\) {- \(\dfrac{5}{2}\); \(\dfrac{3}{2}\)}

M = (\(x\) - 8)(\(x\) + 5) - (\(x\) + 1)(\(x\) - 4)

M = (\(x^2\) + 5\(x\) -8\(x\) - 40) - (\(x^2\) - 4\(x\) + \(x\) - 4)

M = \(x^2\) + 5\(x\) - 8\(x\) - 40 - \(x^2\) + 4\(x\) - \(x\) + 4

M = (\(x^2\) - \(x^2\)) + (5\(x\) - 8\(x\) + 4\(x\) - \(x\)) -  (40 - 4)

M = 0 + (- 3\(x\) + 4\(x\) - \(x\)) - 36

M = (\(x\) - \(x\))  - 36

M = 0 - 36

M =  - 36

Vậy biểu thức M không phụ thuộc vào biến \(x\)

   65 x 56 + 65 x 14 - 35 x 70

= 65 x 56 +  65 x 14 - (65 - 30) x 70

=  65 x 56 +  65 x 14  -  65 x 70 + 30 x 70

= 65 x (56 + 14 - 70) + 30 x 70

= 65 x 0 + 2100

= 0 + 2100

= 2100

 A = \(\dfrac{2}{1\times2}\) + \(\dfrac{2}{2\times3}\) + \(\dfrac{2}{3\times4}\) + \(\dfrac{2}{4\times5}\) + \(\dfrac{2}{5\times6}\)

A = 2 \(\times\) (\(\dfrac{1}{1\times2}\) + \(\dfrac{1}{2\times3}\) + \(\dfrac{1}{3\times4}\) + \(\dfrac{1}{4\times5}\) + \(\dfrac{1}{5\times6}\))

A = 2 \(\times\) (\(\dfrac{1}{1}\) - \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) - \(\dfrac{1}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{4}\) + \(\dfrac{1}{4}\) - \(\dfrac{1}{5}\) + \(\dfrac{1}{5}\) - \(\dfrac{1}{6}\))

A = 2 \(\times\)(\(\dfrac{1}{1}\) - \(\dfrac{1}{6}\))

A  = 2 \(\times\) \(\dfrac{5}{6}\)

A = \(\dfrac{5}{3}\)

                       Giải:

Tiền lãi chiếm số phần trăm số tiền vốn là:

             250 000 : 500 000 = 50

             50 = 50%

Đáp số: 50%

\(\dfrac{\left(1.2+2.3+3.4+4.5+...+98.99\right).x}{26950}\) =   12\(\dfrac{6}{7}\):\(\dfrac{3}{2}\)

\(\dfrac{\left(1.2.3+2.3.3+3.4.3+...+98.99.3\right).x}{26950}\) = 12\(\dfrac{6}{7}\):\(\dfrac{3}{2}\)

\(\dfrac{\left(1.2.3+2.3.4-2.3.1+...+98.99.100-97.98.99\right)x}{26950.3}\) = 12\(\dfrac{6}{7}\):\(\dfrac{3}{2}\)

\(\dfrac{\left(1.2.3-1.2.3\right)+...+\left(97.98.99-97.98.99\right)+98.99.100}{26950.3}x\) = \(\dfrac{90}{7}\):\(\dfrac{3}{2}\)

\(\dfrac{98.99.100}{26950.3}\)\(x\) = \(\dfrac{60}{7}\)

12\(x\) = \(\dfrac{60}{7}\)

    \(x\) = \(\dfrac{60}{7}\) : 12

    \(x\) = \(\dfrac{5}{7}\)

Vậy \(x\) = \(\dfrac{5}{7}\) 

240 = 2⁴.3.5 

Ư(240) ={1;2;3;4;5;6;8;10;12;15;16;20;24;30;40;48;60;80;120;240}

7\(x\).2 hay 7\(x^2\) vậy em?