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GMAT - Data Sufficiency - Algebra

If x = 2t and y = t/3, what is the value of x^2 – y^2?

If x = 2t and y = t/3, what is the value of x^2 – y^2?

(1) t^2 – 3 = 6
(2) t^3 = −27

Given:

x = 2t and y = t/3

x2 - y2 = (2t)2 - (t/3)2 = 4t2 - t2/9 ... required value

Statement 1:

t2 - 3 = 6

t2 = 9

required value = 4t2 - t2 / 9 = 4*9 - 9/9 = 36 - 1 = 35

sufficient

Statement 2

t3 = - 27

t = - 3 (only Real Value)

t2 = 9

Required value = 35 (same as statement 1)

Sufficient