1/Tìm x : x + 4/(5.9)+4/(9.13)+…+4/(41.45)= -37/45 2/Tính: M= 10,25-0,25(3/4+1/2-1/4) P=[(3/5+2/7-1/3)/(6/5+4/7-2/3)] – 1/4

01/11/2021 Bởi Reagan

1/Tìm x :
x + 4/(5.9)+4/(9.13)+…+4/(41.45)= -37/45
2/Tính:
M= 10,25-0,25(3/4+1/2-1/4)
P=[(3/5+2/7-1/3)/(6/5+4/7-2/3)] – 1/4

0 bình luận về “1/Tìm x : x + 4/(5.9)+4/(9.13)+…+4/(41.45)= -37/45 2/Tính: M= 10,25-0,25(3/4+1/2-1/4) P=[(3/5+2/7-1/3)/(6/5+4/7-2/3)] – 1/4”

dananhthu

01/11/2021 vào lúc 23:20

Đáp án:

$\frac{7}{x} + \frac{4}{5.9} + \frac{4}{9.13} + \frac{4}{13.17} + . . . + \frac{4}{41.45} = \frac{29}{45}$

$\Rightarrow \frac{7}{x} + (\frac{4}{5.9} + \frac{4}{9.13} + \frac{4}{13.17} + . . . + \frac{4}{41.45}) = \frac{29}{45}$

$\Rightarrow \frac{7}{x} + (\frac{1}{5} - \frac{1}{9} + \frac{1}{9} - \frac{1}{13} + . . . + \frac{1}{41} - \frac{1}{45}) = \frac{29}{45}$

$\Rightarrow \frac{7}{x} + (\frac{1}{5} - \frac{1}{45}) = \frac{29}{45} \Rightarrow \frac{7}{x} + \frac{8}{45} = \frac{29}{45} \Rightarrow \frac{7}{x} = \frac{29}{45} - \frac{8}{45} \Rightarrow \frac{7}{x} = \frac{21}{45} \Rightarrow \frac{7}{x} = \frac{7}{15} \Rightarrow x = 15$

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