các bạn có biết ( x + 3 ) + ( x + 5 ) + ( x+ 7 ) + ... + ( x + 45 ) = 1210 ko

nếu biết bảo cho tớ nhé tớ đang cần gấp bài này

theo đề ta có 

(3x+2)(x+3) = (0,5x+2)(5x+7) 

=> 3x^2 + 11x + 6 = 2,5x+13,5x+14 

..................

từ đây bn tự giải tìm x

a ) \(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)

\(\Leftrightarrow\left(3x+2\right)\left(5x+1\right)=\left(3x-1\right)\left(5x+7\right)\)

\(\Leftrightarrow3x\left(5x+1\right)+2\left(5x+1\right)=3x\left(5x+7\right)-\left(5x+7\right)\)

\(\Leftrightarrow15x^2+3x+10x+2=15x^2+21x-5x-7\)

\(\Leftrightarrow15x^2+13x+2=15x^2+16x-7\)

\(\Leftrightarrow13x+2=16x-7\)

\(\Leftrightarrow13x-16x=-7-2\)

\(\Leftrightarrow-3x=-9\)

\(\Rightarrow x=3\)

b ) tương tự

\(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\Rightarrow\left(x+1\right)\left(x+3\right)=\left(0,5x+2\right)\left(2x+1\right)\)

\(\Rightarrow x^2+3x+x+3=x^2+0,5x+4x+2\)

\(\Rightarrow x^2+3x+x-x^2-0,5x-4x=2-3\)

\(\Rightarrow-\frac{1}{2}x=-1\)

\(\Rightarrow x=2\)

\(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\)

\(\Rightarrow\left(x+1\right)\left(x+3\right)=\left(2x+1\right)\left(0,5x+2\right)\)

\(\Rightarrow x^2+3x+x+3=x^2+4x+0,5x+2\)

\(\Rightarrow x^2+3x+x+3-x^2-4x-0,5x-2=0\)

\(\Rightarrow1-0,5x=0\)

\(\Rightarrow\frac{1}{2}x=1\Leftrightarrow x=2\)

\(\Leftrightarrow\left(x+1\right)\left(x+3\right)=\left(2x+1\right)\left(x+3\right)\)

\(\Leftrightarrow x^2+4x+3=x^2+4.5x+2\)

\(\Leftrightarrow0.5x+2=3\Leftrightarrow0.5x=1\Leftrightarrow x=2\)

\(\frac{x+1}{2x+1}\)\(=\)\(\frac{0,5x+2}{x+3}\)

  => (x+1).(x+3) = (2x+1).(0,5x+2)

  => x²+4x+3 = x²+4,5x+2

  => x²+4x-x²-4,5x = 2-3

  => -0,5x = -1

 =>  x      = -1:-0,5

 =>  x      = 2 

\(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\)

\(\Leftrightarrow\left(x+1\right)\left(x+3\right)=\left(0,5x+2\right)\left(2x+1\right)\)

\(\Leftrightarrow x^2+3x+x+3=x^2+0,5x+4x+2\)

\(\Leftrightarrow x^2+4x+3=x^2+4,5x+2\)

\(\Leftrightarrow4x+3=4,5x+2\)

\(\Leftrightarrow0,5x=-1\)

\(\Leftrightarrow x=-2\)

Tíck cho mìk vs nha Vân Nguyễn!

Bạn ghi lại đề đi bạn

0.5x=2/3+7/12

1/2x=5/4

x=2.5