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Mathematics - Area Under Curves Question with Solution | TestHub

MathematicsArea Under CurvesArea bounded by two curvesMedium2 minPYQ_2016
MathematicsMediumsingle choice

Area of the region{x,yR2: yx+3,5yx+915}is equal to

Question diagram: Area of the region { x , y ∈ R 2 : y ≥ x + 3 , 5 y ≤ x + 9 ≤

Options:

Answer:
C
Solution:

If x+3<0y (x+3) & y0
If x+30y (x+3) & y0
Also
5yx+915
x5y+90&x6
Intersection point of line & parabolas
5y=x+9& y 2 =| x+3 |(y0)
( x+9 5 ) 2 =| x+3 |
x 2 +18x+81=25x+75or25x75
x 2 7x+6=0or x 2 +43x+156=0
x=1,6orx=39,4
So Clearly,   x=1,y=2
and when  x=4,y=1 are required points
Drawing all these, we get this graph.

Shaded portion is required area.
Clearly required area = area (trapezium ABCD) - A1+A2 .......(i)
area (trapezium ABCD) =121+25=152
A1= -4-3-x+3dx
=23
and A1= -31x+312dx=163
From equation (i), we get required area =152-23+163=32

Stream:JEE_ADVSubject:MathematicsTopic:Area Under CurvesSubtopic:Area bounded by two curves
2mℹ️ Source: PYQ_2016

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