Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202118 MarchMorning Shift
Exam
JEE Main
Year
2021
Date
18 March
Shift
Morning Shift
Subject
Mathematics
Chapter
Quadratic Equation

JEE Main 2021 · 18 March · Morning Shift · Mathematics · Quadratic Equation

The value of 3 + (1)/(4 + (1)/(3 + (1)/(4 + (1)/(3 + ∞)))) is equal...

The value of 3+14+13+14+13+…∞3 + \dfrac{1}{4 + \dfrac{1}{3 + \dfrac{1}{4 + \dfrac{1}{3 + \ldots \infty}}}} is equal to

Options

  1. A1.5+31 . 5 + \sqrt{3}
  2. B2+32 + \sqrt{3}
  3. C3+233 + 2\sqrt{3}
  4. D4+34 + \sqrt{3}

Correct answer

A. 1.5+31 . 5 + \sqrt{3}

Step-by-step solution

Let x=3+14+13+14+13+…∞x = 3 + \dfrac{1}{4 + \dfrac{1}{3 + \dfrac{1}{4 + \dfrac{1}{3 + \ldots \infty}}}}

So, x=3+14+1x=3+14x+1xx = 3 + \dfrac{1}{4 + \dfrac{1}{x}} = 3 + \dfrac{1}{\dfrac{4x + 1}{x}}

⇒(x−3)=x(4x+1)⇒ \left(x - 3\right) = \dfrac{x}{( 4x + 1 )}

⇒(4x+1)(x−3)=x⇒ ( 4x + 1 ) ( x - 3 ) = x

⇒4x2−12x+x−3=x⇒ 4{x}^{2} - 12x + x - 3 = x

⇒4x2−12x−3=0⇒ 4{x}^{2} - 12x - 3 = 0

x=12±(12)2+12×42×4=12±12(16)8x = \dfrac{12 \pm \sqrt{( 12{)}^{2} + 12 \times 4}}{2 \times 4} = \dfrac{12 \pm \sqrt{12 ( 16 )}}{8}

=12±4×238=3±232= \dfrac{12 \pm 4 \times 2\sqrt{3}}{8} = \dfrac{3 \pm 2\sqrt{3}}{2}

x=32±3=1.5±3.x = \dfrac{3}{2} \pm \sqrt{3} = 1 . 5 \pm \sqrt{3} .

But only positive value is accepted

So, x=1.5+3x = 1 . 5 + \sqrt{3}

Practice Quadratic Equation on Quantrex Academy →

More from Quadratic Equation

Match each entry in List-I to the correct entry in List-II and choose the correct option.… JEE Advanced 2026Let a, b, c be positive integers in arithmetic progression such that the equation ax^2 +… JEE Advanced 2026Consider the quadratic equation (n^2 - 2n + 2)x^2 - 3x + (n^2 - 2n + 2)^2 = 0 , n ∈ ℝ .… JEE Main 2026Let one root of the quadratic equation in x : (k^2 - 15k + 27)x^2 + 9(k-1)x + 18 = 0 be… JEE Main 2026Let e_1 and e_2 be two distinct roots of the equation x^2 - ax + 2 = 0 . Let the sets \ a… JEE Main 2026Let α, β be the roots of the equation x^2 - x + p = 0 and γ, δ be the roots the equation… JEE Main 2026Let a, b ∈ ℂ . Let α, β be the roots of the equation x^2 + ax + b = 0 . If β - α = 11 and… JEE Main 2026Let A, B , where A, B ∈ (-(π)/(2), (π)/(2)) , be the roots of the quadratic equation x^2… JEE Main 2026If α=1 and β=1+i 2 , where i= -1 are two roots of the equation x^3+ax^2+bx+c=0 , a,b,c ∈… JEE Main 2026If the quadratic equation (λ+2)x^2-3λ x+4λ=0 , λ ≠ -2 , has two positive roots, then the… JEE Main 2026Let α, β be the roots of the equation x^2 - 3x + r = 0 , and (α)/(2), 2β be the roots of… JEE Main 2026Let a, b, c ∈ \ 1, 2, 3, 4\ . If the probability, that ax^2 + 2 2 \,bx + c > 0 for all x… JEE Main 2026Let S=\ x^ 3 +a x^ 2 +b x+c: a, b, c ∈ ~N. and .a, b, c ≤ 20\ be a set of polynomials.… JEE Main 2026If α, β , where α<β , are the roots of the equation λ x^ 2 -(λ+3) x+3=0 such that… JEE Main 2026The smallest positive integral value of a , for which all the roots of x^ 4 -a x^ 2 +9=0… JEE Main 2026The sum of all the real solutions of the equation _ (x+3) (6 x^ 2 +28 x+30)=5-2 _ (6… JEE Main 2026 Full Quadratic Equation list Quadratic Equation JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs