1/x - 1/y = 1/4
1/x^2 - 1/y^2 = 3/16

x + y = ...

GIVEN:

TO FIND:

ANSWER:

Firstly let us assume ,

Now the equⁿ s becomes ,

=> p - q = 4 . (1)

Also , given that:

=> 1/x² - 1/y² = 3/16.

=> p² - q² = 3/16.

=> (p+q)(p-q) = 3/16.

From (1),

=> 4 (p+q) = 13/16.

=> (p+q) = 13/16 × 1/4.

=> p+ q = 13/64.

On adding (1) and (2) ,

=> 2p = 4 + 13/64.

=> 2p = 256+13/64.

=> p = 269/64 × 1/2.

=> p = 269/128.

Now lets find q ,

=> q = 13/64 - 269/128.

=> q = 26-269/128.

=> q = -243/128.

Hence

.°. x = 128/269 , y = -128/243

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.

step-by-step explanation: