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Solve the equation: x^2 - 9x + 20 = 0

This is a quadratic equation, and is likely that x can satisfy either of two values. We know these must multiply to form 20 and summate to -9, and thus they are (x-4) and (x-5). Hence, x is either 4 or 5.
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Answered by Pippa M. • Maths tutor
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Expand and Simplify: 16=(x-3)(x+3)

16 = (x-3)(x+3) --> 16 = x^2+3x-3x-9 --> 16 = x^2-9 --> x^2=25 --> x = +5 or -5
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Answered by Thaarabi T. • Maths tutor
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Explain how crude oil is split into fractions? Give an example of a substance collected at the top of the column. [5 marks]

Crude oil is made up of a mixture of substances.Crude oil is vapourised before it enters the column.The column is hotter at the bottom and cooler at the top (around 350 degrees at the bottom, and 50 degrees ...
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Give three reasons for why biomass may not be transferred from primary consumers to organisms at higher trophic levels in the food chain. [3 marks]

Some energy is lost via the the primary organism's waste products (such as urine and faeces).Some energy is lost as heat produced as a product of respiration.Energy produced by respiration may be used for mo...
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Answered by Thaarabi T. • Biology tutor
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Prove algebraically that (4n + 1)² − (2n − 1) is an even number for all positive integer values of n.

First of all expand the brackets and simplify the expression given:(4n+1)(4n+1)-(2n-1)= 8n 2 +8n+1-2n+1= 8n 2 +6n+2= 2(4n 2 +3n+1). Since the expression can be factorised with 2, and since 4n 2 +3n+1 will al...
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Answered by Shiv M. • Maths tutor
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