13. Solve the equation 3x = √5(x + 2), giving your answer in the form a + b√5, where a and b are rational.

Rearrange to collect the terms containing x: (3 − √5)x = 2√5. Thus x = 2√5/(3 − √5). Rationalise the denominator:

x = 2√5(3 + √5)/(9 − 5) = (6√5 + 10)/4 = 5/2 + (3/2)√5.