(x + 8) x 16 - x + 15 = 368

16x + 128 - x + 15 = 368

15x = 368 - 128 - 15

15x = 225

x = 225/15

x = 15

(Nhớ k cho mình với nhá!)

a) \(39\times118+29\times82\)

\(=39\times2\times59+29\times2\times41\)

\(=2\times\left(39\times59+29\times41\right)\)

\(=2\times\left(2301+1189\right)\)

\(=2\times3490\)

\(=6980\)

b) \(37\times39+78\times14-13\times85-52\times55\)

\(=37\times3\times13+6\times13\times14+13\times85-4\times13\times55\)

\(=13\times\left(37\times3+6\times14+85-4\times55\right)\)

\(=13\times\left(111+84+85-220\right)\)

\(=13\times\left(280-220\right)\)

\(=13\times60\)

\(=780\)

c) \(368:16+752:16+480:16\)

\(=\left(368+752+480\right):16\)

\(=\left(1120+480\right):16\)

\(=1600:16\)

\(=100\)

d) \(5\times11\times18+9\times31\times10+4\times29\times45\)

\(=5\times11\times9\times2+9\times31\times10+2\times2\times29\times5\times9\)

\(=10\times9\times11+10\times9\times31+10\times29\times2\times9\)

\(=90\times11+90\times31+90\times29\times2\)

\(=90\times\left(11+31+29\times2\right)\)

\(=90\times\left(42+58\right)\)

\(=90\times100\)

\(=9000\)

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

\(\dfrac{4}{3.5}+\dfrac{8}{5.9}+\dfrac{12}{9.15}+...+\dfrac{32}{x\left(x+16\right)}=\dfrac{16}{15}\)

\(2.\left(\dfrac{2}{3.5}+\dfrac{4}{5.9}+\dfrac{6}{9.15}+..+\dfrac{16}{X.\left(X+16\right)}\right)=\dfrac{16}{15}\)

\(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{15}+...+\dfrac{1}{X}-\dfrac{1}{X+16}=\dfrac{8}{15}\)

\(\dfrac{1}{X+16}=\dfrac{1}{3}-\dfrac{8}{15}\)

\(\dfrac{1}{X+16}=\dfrac{-1}{5}\)

\(X+16=-5\)

\(X=-21\)

Tính ngoặc tròn 

\(4\cdot8-16\cdot2\) 

\(=32-32\) 

\(=0\)                                    

Vậy tích trên bằng 0 ( vì có 1 thừa số = 0 ) 

                                                 Bài giải

1 x 2 x 3 x 4 x 5 x 6 x 7 x ( 4 x 8 - 16 x 2 ) x 15 x 16 x 17 ... x 2019 x 2020 

= 1 x 2 x 3 x 4 x 5 x 6 x 7 x ( 32 - 32 ) x 15 x 16 x 17 ... x 2019 x 2020 

= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 0 x 15 x 16 x 17 ... x 2019 x 2020 

= 0

chắt do tui quên tính 4 x 8 - 16 x 2 nên mới vậy :v

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

Giải chi tiết cho mình nha

\(\dfrac{2}{5}+\dfrac{11}{15}=\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)

\(\dfrac{7}{8}-\dfrac{7}{9}=\dfrac{63}{72}-\dfrac{56}{72}=\dfrac{7}{72}\)

\(\dfrac{11}{13}\times\dfrac{26}{31}=\dfrac{22}{31}\)

\(\dfrac{16}{24}:4=\dfrac{16}{24}\times\dfrac{1}{4}=\dfrac{4}{24}=\dfrac{1}{6}\)

\(30:\dfrac{6}{5}=30\times\dfrac{5}{6}=25\)

\(\dfrac{9}{16}:4=\dfrac{9}{16}\times\dfrac{1}{4}=\dfrac{9}{64}\)

\(\dfrac{1}{2}:\dfrac{1}{3}\times\dfrac{8}{15}=\dfrac{1}{2}\times3\times\dfrac{8}{15}=\dfrac{4}{5}\)

2/5 + 11/15 = 17/15
7/8 - 7/9 = 7/72
11/13 x 26/31 = 22/31
16/24 : 4 = 1/6
30 : 6/5 = 25
9/16 : 4 = 9/64
1/2 : 1/3 x 8/15 = 3/2 x 8/15 = 4/5