Number of integral solutions to equation x+y+z=21 , where x ≥ 1, y ≥ 3, z ≥ 4 , is equal to ..

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6.Permutation and Combination

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Number of integral solutions to the equation $x+y+z=21$, where $x \geq 1, y \geq 3, z \geq 4$, is equal to $..........$.

A

$104$

B

$105$

C

$103$

D

$102$

(JEE MAIN-2023)

Solution

${ }^{15} C _2=\frac{15 \times 14}{2}=105$

Standard 11

Mathematics

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