judokan wrote:

If x2/9 – 4/y2 = 12, what is the value of x?

(1) x/3 + 2/y = 6

(2) x/3 – 2/y = 2

x2/9 – 4/y2 = 12 -->

(x/3+2/y)(x/3 - 2/y)=12 --(equation A)

(1) x/3 + 2/y = 6 -----(equation B)

substitute (1) above value into equation (A)

(x/3+2/y)(x/3 - 2/y)=12 --> 6 (x/3 - 2/y)=12

--> x/3 - 2/y =2 --- (equation C)

we have two equations.. two unknowns... must be sufficient

(2) x/3 – 2/y = 2 -- (C)

(x/3+2/y)2=12 --> 2 (x/3 - 2/y)=6

we have two equations.. two unknowns... must be sufficient

Did you observe that

State1 * State 2 = Question..---> then we can say that Answer D...(when State1 & State2 are not quartic/cubic.. higher power.. have only two unknown variables.)

No calculations..required..

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