work out: ( 4 × 10^3 )^2 + 3.5 × 10^7 and give your answer in standard form.

Whenever you have to solve an equation, you must always follow BIDMAS. This means that you should always start with expanding any Brackets, then look at any Indices, then Division, Multiplication, Addition and finally Subtraction. 

For our equation, start off with the brackets. This means work out what 4 * 10^3 is. Following BIDMAS, you have to find 10^3 which is 1000. 4 * 1000 = 4000. Next, work out 4000^2 because you should solve any indices after brackets. 4000^2 = 4000 * 4000 = 16000000. To make it easier leave it as 1.6 * 10^7. Do not add 3.5 to this because you have to follow BIDMAS which means you must do multiplying before addition. 10^7 = 100000000. This is a big number so it will be easier if you leave it as it is - 10^7. (3.5 * 10^7) + (1.6 * 10^7) = 5.1 * 10^7. This is in standard form.