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(2x + 3y)^2 – (2x – 3y)^2 = 360 show that xy is a multiple of 5

Expand first brackets: 4x 2 +6xy+6xy+9y 2 Expand second brackets: 4xy 2 -6xy-6xy+9y 2 Subtract the second expansion from the first one, being careful of the double negative: =24xy Then, back into the origina...
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Answered by Ryan M. • Maths tutor
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Where is DNA found in a human cell? What is a gene?

DNA is a long molecule found in the nucleus (or more specifically the nucleolus) of a human cell. When it is condensed and shortened it appears, under a microscope, as 23 pairs of chromosomes. A gene is a lo...
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Answered by Ryan M. • Biology tutor
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How do I analyse a text to A or A* level?

The examiners are looking for two things from your analysis of a text. Firstly, they want to know that you can identify literary techniques when they are used by the author. Literary techniques dont have to ...
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Answered by Ramganesh L. • English tutor
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Solve the simultaneous equations 5x + 3y = 24 and 3x - 4y = 26

Ok, so here are the equations5x+3y=243x-4y=26So let's multiply the first equation by 3, which gives us:15x+9y=72Now let's multiply the second equation by 5, which gives us:15x-20y=130So we're now left with:1...
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Answered by William S. • Maths tutor
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Why does the solubility of Group 2 hydroxides in water increase down the group?

Firstly, we must consider the thermodynamics involved It is known that a reaction is spontaneous due to thermodynamic favourability if the Gibbs Free Energy is negative. This is further broken down to entrop...
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Answered by Eleni N. • Chemistry tutor
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