Q1. rearange S=2pidsqrthh^2+d^2 i need to make h the subject.
so far i've got s^2=(2pid)^2 (h^2+d^2)
i'm not sure if i'm doing it correctly.
Q2. solve the equation
7/x+2 + 1/x-1 = 4
so far i've got
7x-7 = 4x^2+4x-8 then 4x2-3x-1=0
factorised it
-3+or-(sqrt3^2-4x4x-1)/8
i got x = 0.25 or -1 which i think is wrong.
Q3. bag contains 6 red disks, 4 blue disks and 5 green disks.
A fair dice has 4 red faces and 2 blue faces.
a disk is taken at random from bag and the colour is recorded.
then dice is thrown twice and each time colour of face it lands on is recorded.
work out probability that, of the three colours that are recorded, exactly 2 are the same.