Question

If x is added to each of 14, 12, 34 and
30, the numbers so obtained, in this
order, are in proportion. What is the
value of V12r +9?​

Answer 1

Answer:

81

Step-by-step explanation:

Since on adding x the numbers are in proportion

∴ (14+x) : (12+x) : : (34+x) : (30+x)

⇒ $\frac{14+x}{12+x} =\frac{34+x}{30+x}$

By Componendo & Dividendo we get

$\frac{(14+x)+(12+x)}{(14+x)-(12+x)} =\frac{(34+x)+(30+x)}{(34+x)-(30+x)}$

⇒ $\frac{26+2x}{2} =\frac{64+2x}{4}$

⇒ $26+2x =32+x$

⇒ x = 6

Therefore, the value of 12x+9 = 12×6 + 9 = 72 + 9 = 81

Answer 2

Answer:

81

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