\(B=\left(2+\dfrac{2}{315}\right).\dfrac{1}{651}-\dfrac{1}{105}.\left(3+1-\dfrac{1}{651}\right)-4.\dfrac{1}{315}.\dfrac{1}{651}+\dfrac{4}{105}\)\(=\left(2+\dfrac{2}{3.105}\right).\dfrac{1}{651}-\dfrac{1}{105}.\left(4-\dfrac{1}{651}\right)-4.\dfrac{1}{3.105}.\dfrac{1}{651}+\dfrac{4}{105}\)\(=\left(2+\dfrac{2}{3}.\dfrac{1}{105}\right).\dfrac{1}{651}-\dfrac{1}{105}\left(4-\dfrac{1}{651}\right)-\dfrac{4}{3}.\dfrac{1}{105}.\dfrac{1}{651}+4.\dfrac{1}{105}\)Đặt \(a=\dfrac{1}{105};b=\dfrac{1}{651}\)
\(B=\left(2+\dfrac{2}{3}a\right)b-a\left(4-b\right)-\dfrac{4}{3}ab+4a\)
\(=2b+\dfrac{2}{3}ab-4a+ab-\dfrac{4}{3}ab+4a\)
\(=2b+\dfrac{1}{3}ab\)
Còn lại bạn tự làm nha, mình ko chắc lắm, nếu sai thông cảm nha
