The equation whose roots are the reciprocals of the roots of $3x^2-7x+2=0$ is:

If α and β are the roots then α + β = 7/3 and αβ = 2/3. The new roots 1/α and 1/β have sum (α + β)/(αβ) = 7/2 and product 1/(αβ) = 3/2, so the equation is $x^2-(7/2)x+3/2=0$, i.e. $2x^2-7x+3=0$ — the original coefficients written in reverse order.