Question

Find the value of the following expressions, when x =–1: (i) 2x – 7 (ii) – x + 2 (iii) x2+2x+1 (iv) 2x2–x–2

Answer 1

(i) 2x-7 = 2(-1)-7 = -2-7 = -9 [putting x=-1]

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(ii) -x+2 = -(-1)+2 = 1+2 = 3[putting x=-1]

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(iii) x2+2x+1 = (-1)2+2(-1)+1 = 1-2+1 = 2-2 = 0 [putting x=-1]

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(iv) 2x2-x-2 = 2(-1)2-(-1)-2 = 2×1+1-2 = 2+1-2 = 3-2 = 1 [putting x=-1]