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  9. Q79

RRB NTPC 2021 · Question 79 of 131

What is the square root of the following? (x² –14x+49) (x² + 6x + 9)

  1. A(x–4) (x+9)
  2. B(x–7) (x+3)Correct
  3. C(x–1) (x+17)
  4. D(x–3) (x+8)

Answer: B. (x–7) (x+3)

Explanation

(x² –14x+49) = (x² –7x-7x+49) =x(x-7)-7(x-7) =(x-7) (x-7) (x² + 6x + 9) (x² + 3x+3x+9 =x(x+3) +3(x+3) =(x+3) (x+3) =(x-7) (x+3)

Source: RRB NTPC 2021 CBT 1 Previous Year Paper (3 Feb) — ixambee compilation with answer key · reliable-secondary

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