book Maths Puzzle Numerical Ability

I am not certain of the steps for this;
ar^2 - brs + ars - br^2 = ar^2 + ars - brs - br^2

Thanks,
ttsj

Read Solution (Total 0)

book Other Question

Write an equation of the circle whose center is at the origin and the point (3,-6) is on the circle.

I know the the formula to use is this:

(x-h)squared + (y-k)squared = r squared Write an expression of the sum of 2 consecutive even integres where 2x is the lesser integer
Thank you for your help