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What is the difference between the perfect tense and the imperfect tense?

Both tenses are used to describe something that happened in the past. In every day conversation, the perfect tense is almost always used e.g. j'ai joué, j'ai trouvé.... When writing, the perfect tense is ...

Answered by Antoinette C. • French tutor

2148 Views

Explain why benzene is colourless whereas azo dyes (such as methyl yellow) are coloured.

Azo dyes are coloured because they contain alternating single and double bonds, known as a conjugated system. This creates and areas of delocalisation above and below the plane of the molecule. This area ...

Answered by Amy S. • Chemistry tutor

43076 Views

a) Find the general solution to the differential equation: f(x)=y''-12y'-13y=8. b) Given that when x=0, y=0 and y'=1, find the particular solution to f(x).

First consider y''-12y'-13y=0.

Try: y=e^mx. This gives y'=me^mxand y''=m²e^mx.

Substituting into the differntial equation we get: m²e

Answered by Antonia P. • Further Mathematics tutor

6563 Views

How do I write the function 3cosθ+4sinθ in the form Rsin(θ + α), where R and α are positive constants?

Split it up into steps:

Step 1: Use compound angle trigonometric formula to re-write Rsin(θ + α)

Since generally sin(θ ± φ) = sinθcosφ ± cosθsinφ

Rsin(θ + α) = R(sinθcosα + cos...

Answered by Oliver G. • Maths tutor

12283 Views

Calculate the distance of the centre of mass from AB and ALIH of the uniform lamina.

The diagram shows the lamina shape.

To begin, divide the lamina into smaller sections and calculate the area. In this example, the lamina is best divided into sections A, B and C. Calculate the are...

Answered by Chandler S. • Maths tutor

5611 Views