Question

A varies directly as b square.if b=2,a=8,find a if b=5

Answer 1

Answer :

By the given condition,

a varies directly as b square

⇒ a ∝ b²

⇒ a = k b² ...(i), where k is any constant

When, a = 8 and b = 2,

8 = k × 2²

⇒ 8 = 4k

⇒ k = 8/4

⇒ k = 2

So, k = 2

Putting k = 2 in (i), we get

a = 2 b² ...(ii)

Now, when b = 5, from (ii), we get

a = 2 × 5²

= 2 × 25

= 50

∴ the required value of a is 50

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