19 If 27n×36×2739×814=27, find n 20 Make d the subject of the formula S=n2 2a+n-2d Find - Maths - Representing 3-D in 2-D

Question

19 If 27 n × 3 6 × 27 3 9 × 81 4 = 27 , find
n
20 Make d the subject of the formula S = n 2   2 a +
n - 2 d Find d when S = 256, a = –
4 and n = 16

Neha Sethi · Accepted Answer

Dear student
20
Given formula is :S=n22a+n-2d⇒2Sn=2a+n-2d⇒2Sn-2a=n-2d⇒2Sn-a=n-2d⇒d=2n-2Sn-aSubstituing the values, S=256,a=-4 and n=16d=216-225616--4d=21416+4d=17×20d=207
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19. If 27 n × 3 6 × 27 3 9 × 81 4 = 27 , find n. 20. Make d the subject of the formula S = n 2 2 a + n - 2 d . Find d when S = 256, a = – 4 and n = 16.

19. If $\frac{27^{n} \times 3^{6} \times {(27)}^{3}}{9 \times {(81)}^{4}} = 27$ , find n.
20. Make d the subject of the formula $S = \frac{n}{2} [2 a + (n - 2) d]$ . Find d when S = 256, a = – 4 and n = 16.