Question

1)Tính giá trị biểu thức sau bằng cách hợp lý:

a) \(\dfrac{5}{13}-\dfrac{4}{11}+15+\dfrac{8}{13}-\dfrac{7}{11}\)

2) Tìm x: 

i)\(1\dfrac{3}{4}.\left(x-1\right)+1\dfrac{1}{2}=-0,8\)

Answer 1

Bài 1:

\(\dfrac{5}{13}-\dfrac{4}{11}+15+\dfrac{8}{13}-\dfrac{7}{11}\)

\(=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\left(-\dfrac{4}{11}-\dfrac{7}{11}\right)+15\)

=1-1+15

=15

Bài 2:

\(1\dfrac{3}{4}\left(x-1\right)+1\dfrac{1}{2}=-0,8\)

=>\(\dfrac{7}{4}\left(x-1\right)=-0,8-1,5=-2,3\)

=>\(\left(x-1\right)=-\dfrac{23}{10}:\dfrac{7}{4}=-\dfrac{23}{10}\cdot\dfrac{4}{7}=\dfrac{-23\cdot2}{5\cdot7}=-\dfrac{46}{35}\)

=>\(x=-\dfrac{46}{35}+1=-\dfrac{11}{35}\)

Answer 2

Mọi người ơi, giúp mk 2 câu này với!