\(\left(\frac{2}{11.13}+\frac{2}{13.15}+...+\frac{2}{19.21}\right).462-\left[2.04:\left(x+1,5\right)\right]:0,12=19\)
=> \(\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right).462-\left[2,04:\left(x+15\right)\right]\) \(:0,12=19\)
=> \(\left(\frac{1}{11}-\frac{1}{21}\right).462-\left[2,04:\left(x+15\right)\right]:0,12=19\)
=> \(\frac{10}{231}.462-\left[2,04:\left(x+15\right)\right]:0,12=19\)
=>\(20-\left[2,04:\left(x+15\right)\right]:0,12=19\)
=>\(\left[2,04:\left(x+15\right)\right]:0,12=20-19=1\)
=> \(2,04:\left(x+15\right)=1.0,12=0,12\)
=> \(x+15=2,04:0,12=17\)
=> \(x=17-15=2\)
Vậy x=2
**** đi @nguyentuantai
Cho góc tù xOy bên trong góc xOy Vẽ tia Om và On. Sao cho goc xOm=90 Độ góc yOn bằng 90 đo
a, Chứng minh rằng góc xOn = góc yom
b, Gọi Ot là tia nằm trong góc xOy sao cho góc xOt = góc tOy
\(\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right).462\left[2,04:\left(x+1,5\right)\right]:0,12=19\)
\(\left(\frac{1}{11}-\frac{1}{21}\right).462-\left[2,04:\left(x+1,5\right)\right]:0,12=19\)
\(\frac{10}{231}.462-\left[2,04:\left(x+1,5\right)\right]:0,12\)
\(20-\left[2,04:\left(x+1,5\right)\right]:0,12=19\)
\(\left[2,04:\left(x+1,5\right)\right]:0,12=20-19=1\)
\(2,04:\left(x+1,5\right)=0,12\)
\(x+1,5=2,04:0,12\)
\(x+1,5=17\)
\(x=17-1,5=15,5\)
