`a,`

`13 \times 100 + 2 \times 100 - 9 \times 100`

`= 100 \times (13+2-9)`

`= 100 \times 6`

`= 600`

`b,`

`10 - 8 + 9 - 7 + 6 - 4 + 5 - 3 +2 - 0`

`= (10-8)+(9-7)+(6-4)+(5-3)+2`

`= 2+2+2+2+2`

`= 10`

Ai biết trả lời nhanh giúp mình nha mình đang cần luôn rất rất rất rất gấp.

Ai biết trả lời nhanh giúp mình mình kết bạn cùng

sorry bn nha bài này chịu 

3x1/2x2 x 2x4/3x3 x 3x5/4x4 x....x8x10/9x9 x9x11/10x10

=1/2 x 11/1011/20

a)    \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)

\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)

\(=\frac{1}{2}+\frac{1}{3}\)

\(=\frac{5}{6}\)

b)   \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)

\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)

\(=1\times\frac{1}{2}=\frac{1}{2}\)

c)   \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)

\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)

\(=\frac{247}{420}+\frac{72}{420}\)

\(=\frac{319}{420}\)

còn phần D đâu bn 

tích cho chị nha

 câu a)     = 5/6

 câu b = 1/2

 câu c = 319/420

\(\frac{3}{4}x\frac{8}{9}x\frac{15}{16}x...x\frac{99}{100}=\frac{1x3}{2x2}x\frac{2x4}{3x3}x\frac{3x5}{4x4}x...x\frac{9x11}{10x10}\)

\(=\frac{1x2x3x...x9}{2x3x4x...x10}x\frac{3x4x5x...x11}{2x3x4x...x10}\)

\(=\frac{1}{10}x\frac{11}{2}\)

\(=\frac{11}{20}\)

tớ cũng đang không biết phải giải thế nào

=2x2/1x3 x 3x3/2x4x4/3x5 x ... x 11x11/10x12

=2x2x3x3x4x4x...x11x11/1x3x2x4x3x5x...x10x12

= 2x3x4x...x11)x(2x3x4x...x11)/(1x2x3x4x...x11)/(1x2x3x...x10)x(2x3x4x...x11)

=11x2/1x12

=22/12

=11/6

4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x\(\dfrac{4^2}{3\cdot5}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)

4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)