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If f(x) = 4x - 7 and f(c) = 9, find the value of c.

To find the value of c, we need to find the value of x in the following: 4x - 7 = 9. Add seven to both sides: 4x = 16 Divide by 4: x = 4
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Answered by Andrew B. • Maths tutor
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Factorise and solve x^2 – 8x + 15 = 0

This equation is of the form ax 2 + bx + c = 0 (where a = 1, b = -8 and c = 15). To help solve it, find two numbers that add to give the value of b (the 'sum') and also when multiplied together give the same...
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Answered by Andrew B. • Maths tutor
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Explain how electricity is conducted through a metal. To gain full marks your answer must include a description of the structure and bonding in a metal.

Metals can be described as a lattice of close-packed positive ions in a sea of delocalised electrons. Because the electrons are delocalised, they can move freely through the metal.
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Answered by Andrew B. • Chemistry tutor
15084 Views

There are n sweets in a bag, 6 are orange, the rest yellow. Two sweets are taken out individually without replacement. The probability of which is 1/3. show n²-n-90=0

Firstly, you need to consider the type of problem we are dealing with. This is actually just a tree diagram type question. note that the sweets are not replaced. Letting n = number of sweets in the bag. 6 ar...
JR
Answered by Joel R. • Maths tutor
5089 Views

There are n sweets in a bag. Six of the sweets are orange, the rest are yellow. One sweet is removed from the bag without replacement, then another is removed without replacement. Show that n²-n-90=0

Firstly, you need to consider the type of problem we are dealing with. This is actually just a tree diagram type question. note that the sweets are not replaced. Letting n = number of sweets in the bag. 6 ar...
JR
Answered by Joel R. • Maths tutor
5319 Views