Question

If x > 0 and y >0 and x^9 = 4 and x^7 = 9/y^2, which of the following is an expression for the value of x in terms of y?
(a) (4/9)y
(b) (2/3)y
(c) (3/2)y
(d) 6y
(e) 36y^2

Answer 1

\[x^9=x^(7+2)=x^7x^2=4\] On the other hand
\[x^9=x^7x^2=(9/y^2)x^2=4\]
And the rest should be simple.

Answer 2

is it (a) 4/9y ?