Question

7^x-16y=0
find x-y
plz solve by process

Answer 1

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1

Surose8335

14.10.2018

Math

Secondary School

+5 pts

Answered

If x and y are real numbers such that 7^x -16y=0 and 4^x-49y=0 , then the value of y-x is

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11

abhi178

Given, 7^x - 16y = 0 => 7^x = 16y .....(1)

4^x - 49y = 0 => 4^x = 49y ..........(2)

dividing equation (1) by (1) ,

7^x/4^x = 16y/49y = (4/7)^2

(7/4)^x = (7/4)^-2

x = -2

put x = -2 in equation (1),

7^-2 - 16y = 0

y = 7^-2/16 = 1/(49 × 16)

so, y - x = 1/(49 × 16) - (-2)

= 1/(49 × 16) + 2

= (1 + 49 × 32)/(49 × 16)

= 2.00127551