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What is the subjunctive and when should it be used?

The subjunctive is a mood (not tense) used fairly commonly in Spanish. It can be formed in the present and past tenses (the present form of subjunctive is used when talking about the future also). At GCSE le...
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Answered by Kieran N. • Spanish tutor
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a) You area told that y is proportional to x2 and that when y = 75, x = 5. Find a formula for y in terms of x. y = x b) Find the value of y when x = 3. c) Find the value of x when y = 1200.

a) y is proportional to x^2, when x is 5, y is 75 Therefore: 75 = (something multiplied by) 5^2 75 = 3 x 25 Hence y = 3x^2 b) y = 3 multiplied by 3^2 = 27 c) 1200 = 3x^2 1200/3 = x^2 400 = x^2 Undo the squar...
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Answered by Kezia M. • Maths tutor
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Describe the changes at the cell membrane of a neuron during an action potential.

At rest the membrane potential is -70mV . This is due to the Na + /K + pump, which actively transports 3 Na + ions out of the cell for every 2 K + ions in. Therefore there is a net negative charge inside the...
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Answered by Alex N. • Biology tutor
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What is the mass of an object travelling at 15 m/s with a kinetic energy of 100 J?

Kinetic Energy (E k ) = 1/2(mv 2 ).This can be rearranged such that, m = (2E k )/v 2 we know from the question that E k = 100 J and we know that v = 15 m/sso plugging in the numbers, we get m = (2 x 100)/(15...
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Dipen and Nisha are planning their wedding reception. Nisha says, “I want to invite 70 guests.” Dipen says, “If we invite one-fifth fewer guests, we will save more than £500” Is Dipen correct? (Taken from Nov 2014 AQA Unit 2)

Need to calculate two things in order to answer the question: 1) Total cost of Nisha's 70 guests. 2) Total cost of Dipen's 'one-fifth fewer' guests. For Nishen: Total cost = £40 * 70 minus the 5% reduction =...
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Answered by Alex N. • Maths tutor
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