Question

24. A man saved Rs 32 during first year Rs. 36 in second year and in this way he increases his saving by Rs. 4 every

year find in what time his saving will be Rs 200​

Answer 1

)[2a+(n–1)d]

200=n/2[2×32+(n–1)4]

200×2=n[64+4(n−1)]

400=n[64+4n−4]

400=n[60+4n]

400=4n[15+n]

400/4=15n+n²

100=15n+n²

n²+15n–100=0

n²+20n–5n–100=0

[By middle term splitting]

n(n+20)–5(n+20)=0

(n–5)(n+20)=0

(n – 5) = 0, n = 5 & (n + 20) = 0, n = - 20