A phone contract analyst is simplifying an expression that appears in the spreadsheet used every quarter to model tariff adjustments for existing customers ...
Question 1 Report
A phone contract analyst is simplifying an expression that appears in the spreadsheet used every quarter to model tariff adjustments for existing customers ahead of a pricing review with the company's senior management team: \((x - 3)^2 - (x + 2)(x - 1)\). Expand both brackets and simplify fully, giving your answer in terms of \(x\). (4)
Answer Details
Each bracket is expanded separately first, using \((a-b)^2=a^2-2ab+b^2\) for the square and FOIL for the product of two brackets; the two results are then subtracted, being careful to change the sign of every term inside the second bracket.
\((x-3)^2=x^2-6x+9\) [1 mark]
\((x+2)(x-1)=x^2+x-2\) [1 mark]
Subtracting: \(x^2-6x+9-(x^2+x-2)\) [1 mark]
\(=x^2-6x+9-x^2-x+2=-7x+11\) [1 mark]
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