a) If x=4, work out 3(x^2). b) Solve 6x-3=x+11

a) Our first step is to replace 3(x^2) with 3(4^2) as x=4. Remembering BIDMAS (Brackets, Indices, Division, Multiplication, Addition, Subtraction), we know we must first work out the value of 4 squared, and then multiply that answer by 3. So, 4 squared is equal 44 which equals 16, and 3 multiplied by 16 can be worked out using long division or by adding (310=30) and (3*6=18) which is 48.
b) With algebra, our aim is to isolate 'x' on one side of the = sign and an important rule is anything you do to one side of the equation must be done to the other side. Firstly, it makes sense to subtract x from both sides so that 5x-3=11. Now that we have isolated the unknown x on one side, we can add 3 to both sides of the equation so 5x=14. Now, we must divide both sides by 5 so x=14/5. 14/5 should be re-written as 2 4/5 or 2.8.