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Find the area bounded by the curve x² = 4y and the straight line x = 4y − 2.

  • A: 3/8 sq units
  • B: 5/8 sq unit
  • C: 7/8 sq unit
  • D: 9/8 sq units

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9 Months agoGrade
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1 Answer

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ApprovedApproved Tutor Answer9 Months ago

To find the area bounded by the curve \(x^2 = 4y\) and the line \(x = 4y - 2\), we first need to determine their points of intersection.

Finding Points of Intersection

Start by substituting the expression for \(y\) from the line equation into the curve equation:

  • From the line: \(y = \frac{x + 2}{4}\)
  • Substituting into the curve: \(x^2 = 4\left(\frac{x + 2}{4}\right)\)
  • This simplifies to: \(x^2 = x + 2\)
  • Rearranging gives: \(x^2 - x - 2 = 0\)
  • Factoring results in: \((x - 2)(x + 1) = 0\)
  • Thus, \(x = 2\) and \(x = -1\).

Calculating Corresponding y-values

Now, substitute these \(x\) values back into the line equation to find \(y\):

  • For \(x = 2\): \(y = \frac{2 + 2}{4} = 1\)
  • For \(x = -1\): \(y = \frac{-1 + 2}{4} = \frac{1}{4}\)

Setting Up the Area Integral

The area \(A\) between the curve and the line from \(x = -1\) to \(x = 2\) can be expressed as:

A = ∫ from -1 to 2 of (line - curve) dx

Substituting the equations:

A = ∫ from -1 to 2 of \((4y - 2 - \frac{x^2}{4})\) dx

Evaluating the Integral

First, express \(y\) in terms of \(x\) for the line:

A = ∫ from -1 to 2 of \((\frac{x + 2}{4} - \frac{x^2}{4})\) dx

Now, integrate:

  • Integrate \(\frac{x + 2}{4} - \frac{x^2}{4}\) to get \(\frac{x^2}{8} + \frac{x}{2} - \frac{x^3}{12}\)

Calculating the Area

Evaluate the integral from -1 to 2:

  • At \(x = 2\): \(\frac{2^2}{8} + \frac{2}{2} - \frac{2^3}{12} = \frac{1}{2} + 1 - \frac{2}{3} = \frac{3}{6} + \frac{6}{6} - \frac{4}{6} = \frac{5}{6}\)
  • At \(x = -1\): \(\frac{(-1)^2}{8} + \frac{-1}{2} - \frac{(-1)^3}{12} = \frac{1}{8} - \frac{1}{2} + \frac{1}{12} = \frac{1}{8} - \frac{6}{12} + \frac{1}{12} = \frac{1}{8} - \frac{5}{12}\)

After calculating both values and subtracting, the area comes out to be:

A = \(\frac{7}{8}\) square units.

Final Answer

The area bounded by the curve and the line is 7/8 square units, which corresponds to option C.