\(\frac{1978.1979+1980.21+1958}{1980.1979-1978.1979}\)

\(=\frac{1978.1979+1979.21+21+1958}{1979.\left(1980-1978\right)}\)

\(=\frac{1979.\left(1978+21\right)+21+1958}{1979.2}\)

\(=\frac{1979.\left(1978+21+1\right)}{1979.2}\)

\(=\frac{1979.2000}{1979.2}\)

\(=\frac{2000}{2}\)

\(=1000\)

Đơn giản : 

Ta có :\(\frac{1978.1979+1980.21+1958}{1980.1979-1978.1979}\)

\(=\frac{1978.1979+1979.21+21+1958}{1979\left(1980-1978\right)}\)

\(=\frac{1978.1979+1979.21+1979}{1979.2}\)

\(=\frac{1979.\left(1978+21+1\right)}{1979.2}\)

\(=\frac{2000}{2}=1000\)

cái này cx dễ ợt!tự động não nhóe

thế tính nhanh cho tui

(1980-1978).1979=2.1979=3958

 1980.1979-1978.1979

=(1980-1978)x1979

=2x1979

=3958

1978.1979+1980.21+1958

=3914462+41580+1958

=3956042+1958

=3956240

1980.1979-1978.1979

=3918420-3914462

=3958

li-ke cho mình nha

\(=\frac{1978.1979+1979.21+21+1958}{1979\left(1980-1978\right)}=\frac{1978.1979+1979.22-1979+1979}{2.1979}\)

\(=\frac{1979.\left(1978+22\right)}{2.1979}=\frac{2000.1979}{2.1979}=1000\)

     \(\frac{1978.1979+1980.21+1958}{1980.1979-1978.1979}=\frac{1978.1979+1979.21+21+1958}{1979.\left(1980-1978\right)}\)

\(=\frac{1979.\left(1979+21\right)+21+1958}{1979.2}=\frac{1979.\left(1978+21+1\right)}{1979.2}\)

\(=\frac{1979.2000}{1979.2}=1000.\)

**** nha!

\(\frac{1978.1979+1980}{1980.1979-1978.1979}=\frac{1978.1979+1980}{1979.\left(1980-1978\right)}\)=(Rút gọn,gạch những số giống nhau)=\(\frac{0}{1979}\)

huỳnh thị bích tuyền làm bài sai bét nhào rồi

đáp án la 1000

rút gọn như ông ý là sai oy

Ta có : \(\frac{1978.1979+1980.21+1958}{1980.1979-1978.1979}\)

\(=\frac{1978.1979+\left(1979+1\right).21+1958}{\left(1980-1978\right).1979}\)

\(=\frac{1978.1979+1979.21+1.21+1958}{2.1979}\)

\(=\frac{1979.\left(1978+21\right)+\left(21+1958\right)}{2.1979}\)

\(=\frac{1979.1999+1979}{2.1979}\)

\(=\frac{1979.1999+1979.1}{2.1979}\)

\(=\frac{\left(1999+1\right).1979}{2.1979}\)

\(=\frac{2000.1979}{2.1979}\)

\(=\frac{2.1000.1979}{2.1979}\)

\(=1000\)

222222222222222222222

\(\dfrac{1978.1979+1980.21+1958}{1980.1979-1978.1979}\)

\(=\dfrac{1978.1979+\left(1979+1\right).21+1958}{1979.\left(1980-1978\right)}\)

\(=\dfrac{1978.1979+1979.21+21+1958}{1979.2}\)

\(=\dfrac{1978.1979+1979.21+1979.1}{1979.2}\)

\(=\dfrac{1979.\left(1978+21 +1\right)}{1979.2}\)

\(=\dfrac{1978+21+1}{2}=\dfrac{2000}{2}=1000\)

\(\dfrac{1978.1979+1980.21+1958}{1980.1979-1978.1979}\)

\(=\dfrac{1978.1979+1979.21+21+1958}{1980.1979-1978.1979}\)

\(=\dfrac{1979\left(1978+21\right)+21+1958}{1979\left(1980-1978\right)}\)

\(=\dfrac{1978+21+21+1958}{1980-1978}\)

\(=\dfrac{3978}{2}\)

\(=1989\)