Find the area of the region enclosed by the parabola x2 = y and the line y = x + 2
x2 = y parabola is not defined for negative values of y hence parabola will be above X-axis opening upwards and passing through (0, 0)
y = x + 2 is a straight line
plot these equations and we have to find the area enclosed between them
To find the intersection points solve the equations x2 = y and y = x + 2 simultaneously
Put y = x + 2 in x2 = y
⇒ 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 and x = 2 in x2 = y we get y = 1 and y = 4 respectively
Hence (-1, 1) and (2, 4) are the points at which the line intersects the parabola
⇒ area enclosed by line and parabola = area under line – area under parabola …(i)
Let us find area under line y = x + 2
⇒ y = x + 2
Integrate from -1 to 2
Now let us find area under the parabola
x2 = y
⇒ y = x2
Integrate from -1 to 2
Using (i)
⇒ area enclosed by line and parabola = – 3 = unit2
Hence area enclosed is unit2