Y x 1 + Y x 2 + Y x 3 + ... + Y x 100 = 12625

Y x (1+2+3+...+100) = 12625

Y x (100+1) x (100:2) = 12625

Y x (101 x 50) = 12625

Y x 5050 = 12625

Y= 12625 : 5050

Y= 2,5

\(y\times1+y\times2+y\times27-\left(99-22\right)=277\)

\(y\times\left(1+2+27\right)-77=277\)

\(y\times30-77=277\)

\(y\times30=277+77\)

\(y\times30=354\)

\(y=\dfrac{354}{30}\)

\(y=\dfrac{59}{5}\)

y x 3 + y x 2 = 58 - ( 15 + 4 + 9 )

y x 5 = 28

y = 28 : 5 

y = 5,6

HT

 y * 1 + y * 2 + y * 3 + y * 4 + y *1 = 825

y * ( 1 + 2 + 3 + 4  + 1) =825

y * 11 = 825

        y = 825 / 11

         y = 75   

y × 2/3 - 2/3 = 9/12

y × 2/3 = 9/12 + 2/3

y × 2/3 = 9/12 + 8/12

y × 2/3 = 17/12

y = 17/12 : 2/3

y = 17/8

\(\dfrac{2}{3}\left(y-1\right)=\dfrac{9}{12}\)

\(y-1=\dfrac{3}{4}:\dfrac{2}{3}\)

\(y-1=\dfrac{9}{8}\)

\(y=\dfrac{9}{8}+1\)

\(y=\dfrac{17}{8}\)

a) 8/15 + 1 = 23/15

b) 3/14 + 11/14 - 2/3 = 1- 2/3 = 1/3

c) 7/15 * (5/3+2/3) = 7/15 * 7/3= 49/45

d) 6/11 + 5/11 - 3/5 = 1 - 3/5 = 2/5

a=23/18

b=1/3

c=49/4

d=2/5

a) \(\frac{2}{3}-4.\left(\frac{1}{2}+\frac{3}{4}\right)\)

= \(\frac{2}{3}-4.\frac{5}{4}\)

= \(\frac{2}{3}-5\)

= \(-\frac{13}{3}\).

b) Câu này là 117 hay \(\frac{11}{7}\) vậy bạn?

Chúc bạn học tốt!