Question 2n-2-3n-4-5n-6-21

N/2 3n/4+5n/6=21 ⇒6n 9n+10n/12=21 ⇒7n/12=21 ⇒ n=21 × 12/7⇒ n=36 To check: n/2 3n/4+5n/6=21 ⇒36/2 3 × 36/4+5 × 36/6=21 ⇒ 18 27+30=21 ⇒ 21=21 ⇒ LHS.=R.H.S Theref ...

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Standard VII

Mathematics

Addition of Algebraic Expression

Question 2n/2...

Question

Question 2
$\frac{n}{2} - \frac{3 n}{4} + \frac{5 n}{6} = 21$

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Solution

$\frac{n}{2} - \frac{3 n}{4} + \frac{5 n}{6} = 21$
$\Rightarrow \frac{6 n - 9 n + 10 n}{12} = 21 \Rightarrow \frac{7 n}{12} = 21$
$\Rightarrow n = \frac{21 \times 12}{7} \Rightarrow n = 36$
To check:
$\frac{n}{2} - \frac{3 n}{4} + \frac{5 n}{6} = 21 \Rightarrow \frac{36}{2} - \frac{3 \times 36}{4} + \frac{5 \times 36}{6} = 21$
$\Rightarrow 18 - 27 + 30 = 21 \Rightarrow 21 = 21$
$\Rightarrow L H S . = R . H . S$
Therefore, it is correct.

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Addition of Algebraic Expression

Standard VII Mathematics

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Question 2 n2−3n4+5n6=21

n2−3n4+5n6=21 ⇒6n−9n+10n12=21⇒7n12=21 ⇒n=21×127⇒n=36 To check: n2−3n4+5n6=21⇒362−3×364+5×366=21 ⇒18−27+30=21⇒21=21 ⇒LHS.=R.H.S Therefore, it is correct.

Question 2
$\frac{n}{2} - \frac{3 n}{4} + \frac{5 n}{6} = 21$