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What are the three isolation barriers by which speciation can occur?

Speciation is a complex topic, and indeed what defines a species is still debated today. However, one factor is key to the process of speciation; gene flow. Gene flow between populations of a species ensures...
JM
Answered by John M. • Biology tutor
21492 Views

Sketch the curve y = (x^2 - 9)(x - 2)

When it comes to curve sketching, there are a number of tests that you can do to find out crucial characteristics about the curve. They are following: 1. Setting x = 0 will give you the points at which the c...
DS
Answered by Dan S. • Maths tutor
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Is it important to include opinions of historians in my essays?

Historical opinion - also known as historiography - is essential to essay writing. Including the opinions and arguments of historians shows your awareness of the field. It will impress your examiners if you ...
LH
Answered by Luke H. • History tutor
11425 Views

Given that 4(cosec x)^2 - (cot x)^2 = k, express sec x in terms of k.

This question makes good use of the trigonometric identities tan 2 x + 1 = sec 2 x and 1 + cot 2 x = cosec 2 x which can be easily recited in the exam by using the identity sin 2 x + cos 2 x = 1 and then div...
DS
Answered by Dan S. • Maths tutor
13304 Views

Find the gradient of the line 4x+9y=10.

There are two approaches to this problem. Firstly, you could rearrange the equation so that you have the general equation of a line, y=mx+c, where m is the gradient that you are looking for! When we rearrang...
DS
Answered by Dan S. • Maths tutor
5353 Views