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प्रश्न
Find the total number of ways in which six '+' and four '−' signs can be arranged in a line such that no two '−' signs occur together.
उत्तर
Six '+' signs can be arranged in a row in\[\frac{6!}{6!}\] = 1 way
Now, we are left with seven places in which four different things can be arranged in 7P4ways.
Since all the four '- ' signs are identical, four '- ' signs can be arranged in\[{{7}{}{P}_4}{4!}\]ways, i.e. 35 ways.
Number of ways = 1\[\times\]35 = 35
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