13*15+14=14*15-1=1

\(\frac{15\times14-1}{13\times15+14}\)

\(=\frac{15\times\left(13+1\right)-1}{13\times15+14}\)

\(=\frac{15\times13+15-1}{15\times13+14}\)

\(=\frac{15\times13+14}{15\times13+14}\)

\(=1.\)

=210 - 210 / 13

=2520 / 13

nha tui ít điểm

\(\frac{14}{13}\) x \(\frac{15}{14}\) x \(\frac{16}{15}\) x ... x \(\frac{2014}{2013}\)x \(\frac{2015}{2014}\)

=  \(\frac{14x15x16x...x2013x2014x2015}{13x14x15x16x...x2013x2014}\)

= 14 x 2015

=28210

11 + 15 + 12 + 14 + 19 + 15 + 18 + 16 + 35

= ( 11 + 19 ) + ( 15 + 15 ) + ( 12 + 18 ) + ( 14 + 16 ) + 35

= 30 + 30 + 30 + 30 + 35

= 30 x 4 + 35

= 120 + 35

= 155

Chúc bạn học tốt!

11+15+12+14+19+15+18+16+35

=(11+19)+(15+15)+(12+18)+(14+16)+35

=    30   +    30    +    30   +     30   +35

=          60           +          60          +35

=                       120         +              35

=      155

13x11+14x11+15x11

=(13+14+15)x11

=42x11

=462

13 x 11 + 14 x 11 + 15 x 11

= 11 x ( 13 + 14 + 15 )

= 11 x 42

= 462

~ Ủng hộ nhé ~

báo cáo nhé?

 the only 

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(14,78-a)/(2,87+a)=4/1

14,78+2,87=17,65

Tổng số phần bằng nhau là 4+1=5

Mỗi phần có giá trị bằng 17,65/5=3,53

=>2,87+a=3,53

=>a=0,66.

10 * 11 * 12 * 13 * 14 * 15 = 3603600

a)\(x+\frac{15}{16}+\frac{7}{8}=\frac{15}{4}\)

\(x+\frac{29}{16}=\frac{15}{4}\)

\(x=\frac{15}{4}-\frac{29}{16}\)

\(x=\frac{31}{16}\)

b)\(x-\frac{27}{28}-\frac{9}{14}=\frac{13}{7}\)

\(x-\frac{45}{28}=\frac{13}{7}\)

\(x=\frac{13}{7}+\frac{45}{28}\)

\(x=\frac{97}{28}\)

c)\(x\times\frac{1}{5}+x+\frac{1}{6}=\frac{2}{3}\)

\(x\times\frac{1}{5}+x=\frac{2}{3}-\frac{1}{6}\)

\(x\times\left(\frac{1}{5}+1\right)=\frac{1}{2}\)

\(x\times\frac{6}{5}=\frac{1}{2}\)

\(x=\frac{1}{2}:\frac{6}{5}\)

\(x=\frac{5}{12}\)

d)\(x:14=\frac{1}{4}+\frac{2}{9}+\frac{3}{4}\)

\(x:14=\frac{11}{9}\)

\(x=\frac{11}{9}\times14\)

\(x=\frac{154}{9}\)

#H