Q.

Let P1:y=4x2  and  𝑃2:𝑦=𝑥2+27 be two parabolas. If the area of the bounded region enclosed between P1 and P2 is six times the area of the bounded region enclosed between the line y=αx, α>0 and P1, then α is equal to :   [2026]

1 15  
2 12  
3 8  
4 6  

Ans.

(2)

Area bounded between P1 & P2 is

∫-33((x2+27)-(4x2))dx

                     (P.O.I. of P1 & P2 is x=±3)

=2∫03(27-3x2)dx=2[27x-x3]03

=2[81-27]=108

∴ Area bounded between P1 & L is 18 sq. units

(Area between x2=4ay & line x=my is 8a23m3)

∴ Area between x2=y4 & x=yα is

8(116)23(1α)3=18

⇒816·163α3=18⇒α3=26·33

⇒α=12