Question

7^x-y = 49 and 7^x+y = 343 find value of 6x+2y

Answer 1

ur answer ..........

Answer 2

The value of 6x + 2y is 16.

Given,

7^x-y = 49 and 7^x+y = 343

To Find,

The value of 6x + 2y.

Solution,

We have, 7^x-y = 49

⇒ 7^x-y = 7^2

⇒ x-y = 2                         -----------------------------------------(1)

Also, 7^x+y = 343

⇒ 7^x+y = 7^3

⇒ x+y = 3                        -----------------------------------------(2)

On adding (1) and (2), we get,

⇒ x-y + x+y = 2 + 3

⇒ 2x = 5

⇒ x = 5/2

On putting value of x in (2), value of y is,

⇒ 5/2 + y = 3

⇒ y = 1/2

Now, 6x + 2y

⇒ 6(5/2) + 2(1/2)

⇒ 3x5 + 1

⇒ 15 +1 = 16

Hence, the value of 6x + 2y is 16.

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