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← JEE Main 2022 · 24 Jun · Shift 1
MathematicsInteger+4 / -1Question 29 of 90

JEE Main 2022 · 24 Jun · Shift 1, Mathematics question 29

Let SS be the region bounded by the curves y=x3y=x^3 and y2=xy^2=x. The curve y=2∣x∣y=2|x| divides SS into two regions of areas R1R_1 and R2R_2.

If max⁡{R1,R2}=R2\max\{R_1,R_2\}=R_2, then R2R1\dfrac{R_2}{R_1} is equal to ______.

Answer and worked solution

Official answer: 19

Region S. Between y=x3y=x^3 (below) and y=xy=\sqrt x (above) for 0≤x≤10\le x\le1: area 23−14=512\frac23-\frac14=\frac5{12}.

The cut. For x≥0x\ge0, y=2xy=2x meets y=xy=\sqrt x at x=14x=\frac14 and stays above y=x3y=x^3 on [0,1][0,1] (they meet only at x=2x=\sqrt2). So it cuts off the piece between y=2xy=2x and y=xy=\sqrt x on [0,14][0,\frac14]:
R1=∫01/4(x−2x) dx=112−116=148.R_1=\int_0^{1/4}(\sqrt x-2x)\,dx=\frac1{12}-\frac1{16}=\frac1{48}.

Ratio. R2=512−148=1948R_2=\frac5{12}-\frac1{48}=\frac{19}{48}, so R2R1=19\frac{R_2}{R_1}=19.

Answer: 19