Hi, if you are intending to use the special algebraic identities, a quick help/shortcut would be to check if the term in x^2 and constant terms are square numbers. In 8(a), 4x^2 is a square number (2x)^2 and 25 is also a square number. As a Sec2 student, it's good to practice this step by step first, don't jump steps!
In 8(b), all you need to do it flip the divide sign, and simplify. I like to combine everything before I "cancel" out common terms!

Hope it helps!