Use completing square method to solve the equation, 3x2 − 7x + 2 = 0.

Take half of the coefficient of $x$, square it, and add it to both sides.
The coefficient of $x$ is $-\frac{7}{3}$. Half of it is $-\frac{7}{6}$. Squaring it gives $(-\frac{7}{6})^2 = \frac{49}{36}$.

For the positive root:

For the negative root:

The solutions are $\boxed{x=2 \text{ or } x=\frac{1}{3}}$.

2. Solve for $x$, $(\frac{2}{3})^{2x} \times 36^x = 64$.

The solution is $\boxed{x=\frac{3}{2}}$.

3. The figure below shows a triangle PQR given that PQ = PR = 12cm, TR = 4cm, ST = 6cm and ST is parallel to QR. Calculate the perimeter of the quadrilateral QRTS.

$PQ = 12$ cm
$PR = 12$ cm
$TR = 4$ cm
$ST = 6$ cm
$ST \parallel QR$

Since $PR = PT + TR$, we have:

Since $ST \parallel QR$, triangle $PST$ is similar to triangle $PQR$ ($\triangle PST \sim \triangle PQR$).
The ratio of corresponding sides is equal:

Since $PQ = PS + SQ$, we have:

The perimeter is the sum of its sides: $QR + RT + TS + SQ$.

The perimeter of quadrilateral QRTS is $\boxed{23 \text{ cm}}$.