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How do I expand double brackets? E.g. (4x+7)(3x+5)

In order to expand the brackets, we need to ensure that EVERYTHING in the left bracket is multiplied by EVERYTHING in the right bracket. There are 3 methods for helping us to times out the brackets. These ar...
SA
Answered by Shona A. • Maths tutor
6869 Views

Elemental analysis of a carbohydrate X showed the sample contained 48.7 % carbon and 8.1 % hydrogen by mass. Find the empirical formula of X.

These sorts of questions can look difficult, but if you learn the steps needed to solve them then they are all very similar. Step 1: Since we are told that X is a carbohydrate, we know that the only other co...
JB
Answered by Jack B. • Chemistry tutor
2176 Views

2NaNO3 --> 2NaNO2 + O2. When a sample of solid sodium nitrate was heated 96cm3 of gas was collected, calculate the mass of NaNO3 Decomposed

We know that the reaction is a 2:1 ratio as 2 moles of NaNO3 is used to form 1 mole of O2 so first we need to find the moles of the product produced SoVolume of gas (dm3)= number of moles x 24dm3Therefore vo...
SZ
Answered by Sara Z. • Chemistry tutor
11525 Views

How do I use the perfect tense in French?

The perfect tense in French has two parts. The first is the auxillary or first verb, which you will probably be familiar with, which takes the form of avoir (to have) or être (to be). You change this first v...
MB
Answered by Maisie B. • French tutor
2263 Views

How do I differentiate between the articles le/la/les/un/une/des and when to use them?

These articles are used before a noun, the same way you would typically use the word "the" or "a" in English. Their use will depend on 2 characteristics of the noun they are used with: 1)...
SR
6155 Views