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If y=x^3+9x, find gradient of the tangent at (2,1).

To find the gradient of the tangent, we can differentiate to give dy/dx=3x^2+9. We can now put in x=2 to find the gradient at (2,1): 3(2)^2+9=21. Therefore the gradient is 21 at (2,1).
AM
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Solve 7x-4=8+5x

First bring all the x terms to one side by taking 5x from each side, this gives 2x-4=8. Now put all the number terms on the other side by adding 4 to each side, this gives 2x=12. We can now divide both sides...
AM
Answered by Angus M. • Maths tutor
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For a named country which you have studied, describe the problems caused by an ageing population.

Name of country: Japan Japan has a population of 127 million and roughly 23% are over the age of 65 and this huge proportion can prove to be problematic. In general, the elderly require more expensive health...
NC
Answered by Natasha C. • Geography tutor
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How do viruses cause disease?

A virus is an example of a pathogen. Pathogens also include bacteria, fungi or protists, and all are capable of causing infectious disease. Viruses are very small, much smaller than bacteria. They consist of...
KG
Answered by Kavindi G. • Biology tutor
13874 Views

Explain how changes to the guard cells on the warm day help the plant to survive

the points you need to get accross here are; -on a warm day, there will be more evaporation from the plant, -therefore the guard cells will close around the stomata so that the plant will not lose too much w...
ES
Answered by Ella S. • Biology tutor
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