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Algebraic Expressions and Identities — MATHS STD 8 — Question

Gujarat BoardEnglish MediumSTD 8MATHSAlgebraic Expressions and Identities1 Mark
MCQ
Simplify $4x(5x^2 + 3x) + 2x$ and find its value for $x = 2$
  • A
    $20x^3+ 12x^2 + 2x 211$
  • B
    $20x^3 + 20x^2 ; 240$
  • C
    $20x^2 + 20x ; 120$
  • ✓
    $20x^3 + 12x^2 + 2x ; 212$
✓

Answer

Correct option: D.
$20x^3 + 12x^2 + 2x ; 212$
D.  $20x^3 + 12x^2 + 2x ; 212$
Solution:
Simplifying the given expression, $4x(5x^2) + 4x(3x) + 2x = 20x^3 + 12x^2 + 2x$
For $x = 2,$ the value of expression $= 20(2)^3 + 12(2)^2 + 2(2) = 20 \times 8 + 12 \times 4 + 4 = 160 + 48 + 4 = 212$

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