Question

Cảm ơn các bn đã giúp mk mấy câu kia mk có câu mới nè!

Answer 1

Không ngờ đôi khi ngonhuminh cũng làm sai!

Giải:

Do \(\dfrac{1+2y}{18}=\dfrac{1+4y}{24}\)

\(\Leftrightarrow24\left(1+2y\right)=18\left(1+4y\right)\)

\(\Leftrightarrow24+48y=18+72y\)

\(\Leftrightarrow24y=6\Rightarrow y=\dfrac{1}{4}\) thay vào đề bài ta có:

\(\dfrac{1+2.\dfrac{1}{4}}{18}=\dfrac{1+6.\dfrac{1}{4}}{6x}\Rightarrow\dfrac{\dfrac{3}{2}}{18}=\dfrac{\dfrac{5}{2}}{6x}\)

\(\Rightarrow\dfrac{3}{2}.6x=\dfrac{5}{2}.18\Rightarrow\dfrac{3}{2}.6x=45\Leftrightarrow x=5\)

Vậy \(x=5\)

Answer 2

\(\dfrac{1}{18}=\dfrac{1+4y}{24}=\dfrac{1+6y}{6x}=\dfrac{1+2y+\left(1+4y\right)-\left(1+6y\right)}{18+24-6x}=\dfrac{1}{18+24-6x}\)

\(\Rightarrow18+24-6x=18\Rightarrow x=\dfrac{24}{6}=4\)

Answer 3

Đề to quá chê hết cả màn hình

\(\dfrac{1+2y}{18}=\dfrac{1+4y}{24}=\dfrac{1+6y}{6x}=\dfrac{1}{18+24-6x}\Rightarrow\dfrac{1}{42-6x}\)

\(\dfrac{2+4y}{36}=\dfrac{1+4y}{24}=\dfrac{1}{12}\)

\(\dfrac{1}{42-6x}=\dfrac{1}{12}\Rightarrow24-6x=12\Rightarrow x=2\)

Answer 4

Theo định nghĩa hai phân số bằng nhau ta có:

\(\dfrac{1+2y}{18}=\dfrac{1+4y}{24}\) khi và chỉ khi:

\(\left(1+2y\right)\cdot24=\left(1+4y\right)\cdot18\)

\(\Rightarrow24+48y=18+72y\)

\(\Rightarrow72y-48y=24-18\)

\(\Rightarrow24y=6\)

\(\Rightarrow y=\dfrac{6}{24}=\dfrac{1}{4}\)

Lại có: \(\dfrac{1+4y}{24}=\dfrac{1+6y}{6x}\)

\(\Rightarrow\dfrac{1+4\cdot\dfrac{1}{4}}{24}=\dfrac{1+6\cdot\dfrac{1}{4}}{6x}\)

\(\Rightarrow\dfrac{1}{12}=\dfrac{\dfrac{5}{2}}{6x}\)

\(\Rightarrow6x\cdot1=12\cdot\dfrac{5}{2}\)

\(\Rightarrow x=30:6=5\)

Vậy x = 5; y = \(\dfrac{1}{4}\)