tìm x:
$\frac{7}{x}$+$\frac{4}{13.17}$+$\frac{4}{17.21}$+$\frac{4}{21.25}$+…+$\frac{4}{45.49}$ =$\frac{151}{637}$
tìm x:
$\frac{7}{x}$+$\frac{4}{13.17}$+$\frac{4}{17.21}$+$\frac{4}{21.25}$+…+$\frac{4}{45.49}$ =$\frac{151}{637}$
`7/x + (4/13.17 + 4/17.21 +…+4/45.49)= 151/637`
`7/x + ( 1/13 – 1/17 + 1/17 – 1/21 +…+1/45 – 1/49) = 151/637`
`7/x+ ( 1/13 – 1/49) = 151/637`
`7/x + 36/637 = 151/637`
`7/x= 151/637 – 36/637`
`7/x= 115/637`
`x= 7 : 115/637`
`x= 7. 637/115`
`x= 4459/115`
Vậy `x= 4459/115`
Đáp án:
`x= 4459/115 `
Giải thích các bước giải:
` 7/x + 4/(13.17) + 4/(17.21) + 4/(21.25) + … + 4/(45.49) = 151/637`
`7/x + ( 1/13 – 1/17 + 1/17 – 1/21 +…+1/45 – 1/49) = 151/637`
` 7/x + ( 1/13 – 1/49 ) = 151/637 `
` 7/x + 36/637 = 151/637 `
` 7/x= 151/637 – 36/637`
`7/x= 115/637`
` x . 115 = 7 . 637 `
`x.115 = 4459 `
`x = 4459 : 115 `
`x= 4459/115 `