i) Make y the subject of the expression x = ((a-y)/b))^1/2 ii) Simplify fully (2x^2 − 8)/(4x^2 − 8x)

i) Square both sides of the expression to make x^2=(a-y)/b 

Multiply by b to remove the fraction from the equation and then rearrange to make y the subject.

bx^2=a-y --> y=a-bx^2

ii) First factor out 2 from the numerator to make 2(x^2-4)

Factorize x^2 -4 to (x+2)(x-2) thereby writing the numerator as 2(x+2)(x-2)

Recognize that 4x is the common factor in the demoninator and thereby write the fraction as 2(x+2)(x-2)/4x(x-2)

Cancel the (x-2) from the top and bottom and then rerwite 2(x+2)/4x as x+2/2x