Question

tính 1998*1990+3978\1992*1991-3984=

Answer 1

Mik sửa lại đề

\(\frac{1989.1990+3978}{1992\cdot1991-3984}\)

Trả lời

\(\frac{1989.1990+3978}{1992.1991-3984}\)

\(=\frac{1989.1990+1989\cdot2}{1992.1991-1992.2}\)

\(=\frac{1989.\left(1992-2\right)}{1992\left(1991-2\right)}\)

\(=\frac{1989.1990}{1992.1989}\)

\(=\frac{1990}{1992}\)

\(=\frac{995}{996}\)