1a) Simplify (5x^2/8y) / (4/5x^2y)^-2.
b) Factoris a^2-ac-25b^2 + 5bc
2) The number of sides of a regular polygon X is doubled to form a new regular polygon Y. If the ratio of each interior angle of the polygon X to that of the polygon Y is 4:5. Find the number of sides of polygon X.
b) hence find the size of each exterior angle of polygon Y.
3)It is known that y>0 and it varies inversely as the square of (x-2).Given that difference between the values of y when x = 3 and when x=7 is 24/5. Find the value of y when x = 12.
4)Solve the equation 4^(x^2 - 3) = 8^5x/3 + 3
Lastly,how do you all study for chemistry and biology. I don't know how to prepared O level for science sia. Any guides?