Find the area enclosed by the curve y = –x2 and the straight lilne x + y + 2 = 0.

y = -x2 x2 = -y


x2 = -y parabola is not defined for positive values of y hence parabola will be below X-axis opening downwards and passing through (0, 0)


x + y + 2 = 0 is a straight line


To find point of intersection of parabola and straight line solve the parabola equation and the straight line equation simultaneously


Put y = -(x + 2) in x2 = -y


x2 = -(-(x + 2))


x2 = x + 2


x2 – x – 2 = 0


x2 – 2x + x – 2 = 0


x(x – 2) + 1(x – 2) = 0


(x + 1)(x – 2) = 0


x = -1 and x = 2


Put x = -1 in x2 = -y


(-1)2 = -y


y = -1


Put x = 2 in x2 = -y


22 = -y


y = -4


Hence the parabola and line intersects at (-1, -1) and (2, -4)


Plot the parabola and straight line and the bounded area is as shown



area enclosed by line and parabola = area under line – area under parabola …(i)



Let us find area under the straight line


x + y + 2 = 0


y = -(x + 2)


Integrate from -1 to 2








Now let us find area under parabola


x2 = -y


y = -x2


Integrate from -1 to 2







Using (i)


area enclosed by line and parabola = = unit2


We are getting negative sign because the area is below X-axis as seen in figure


Hence area enclosed is unit2


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