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SSC CGL 2025 PYQ — Question 58

SSC CGL - 21 Sep 2025 - Shift 2 • Quantitative Aptitude • Q58

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Simplify the expression: (2.3)3+(15.9)3+(3.7)3−3×2.3×15.9×3.7(2.3)2+(15.9)2+(3.7)2−2.3×15.9−15.9×3.7−3.7×2.3{(2.3)^3+(15.9)^3+(3.7)^3-3\times2.3\times15.9\times3.7}\over{(2.3)^2+(15.9)^2+(3.7)^2-2.3\times15.9-15.9\times3.7-3.7\times2.3}

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Correct answer: D

Explanation

The correct answer is option 4 i.e. 21.9

We know that,

a3 + b3 + c3 - 3abc = (a + b + c)(a2 + b2 + c2 - ab - bc - ca)

⇒ (2.3)3+(15.9)3+(3.7)3−3×2.3×15.9×3.7(2.3)2+(15.9)2+(3.7)2−2.3×15.9−15.9×3.7−3.7×2.3{(2.3)^3+(15.9)^3+(3.7)^3-3\times2.3\times15.9\times3.7}\over{(2.3)^2+(15.9)^2+(3.7)^2-2.3\times15.9-15.9\times3.7-3.7\times2.3}

⇒ (2.3+15.9+3.7)((2.3)2+(15.9)2+(3.7)2−2.3×15.9−15.9×3.7−3.7×2.3)((2.3)2+(15.9)2+(3.7)2−2.3×15.9−15.9×3.7−3.7×2.3){(2.3+15.9+3.7)((2.3)^2+(15.9)^2+(3.7)^2-2.3\times15.9-15.9\times3.7-3.7\times2.3})\over({(2.3)^2+(15.9)^2+(3.7)^2-2.3\times15.9-15.9\times3.7-3.7\times2.3})

⇒ 2.3 + 15.9 + 2.3 = 21.9