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Vector Algebra

Question
CBSEENMA12032817

The area bounded by the curve y = x |x|, x-axis and the ordinates x = - 1 and x = 1 is given by
  • 0

  • 1 third
  • 2 over 3
  • 4 over 3

Solution

C.

2 over 3

We want to find the area bounded by the curve straight y equals straight x space open vertical bar straight x close vertical bar comma x-axis and the ordinates x = -1 and x = 1
Required area = integral subscript negative 1 end subscript superscript 1 space straight y space dx space equals space integral subscript negative 1 end subscript superscript 1 space straight x space open vertical bar straight x close vertical bar space dx
              equals space integral subscript negative 1 end subscript superscript 0 open vertical bar straight x open vertical bar straight x close vertical bar close vertical bar space dx space plus space integral subscript 0 superscript 1 space straight x space open vertical bar straight x close vertical bar space dx
                                      open square brackets because space space space open vertical bar straight x space open vertical bar straight x close vertical bar close vertical bar space equals space open vertical bar straight x close vertical bar space open vertical bar straight x close vertical bar space equals straight x squared close square brackets
                 equals space integral subscript negative 1 end subscript superscript 0 left parenthesis straight x squared right parenthesis dx plus integral subscript 0 superscript 1 straight x squared dx space equals space open square brackets straight x cubed over 3 close square brackets subscript negative 1 end subscript superscript 0 plus open square brackets straight x cubed over 3 close square brackets subscript 0 superscript 1
equals space open square brackets 0 minus fraction numerator left parenthesis negative 1 right parenthesis cubed over denominator 3 end fraction close square brackets plus open square brackets 1 third minus 0 close square brackets space equals space 1 third plus 1 third equals 2 over 3

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