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Linear and Quadratic Equations · Question 53 of 66

Question 53

HardOriginal question

Which equation has roots that are the reciprocals of the roots of 2x2−7x+3=02x^2 - 7x + 3 = 0?

Options for question 53

Show the answer and explanation
CorrectNot quiteAnswer C

Correct answer: C

Explanation

  1. 2x2−7x+3=(2x−1)(x−3)2x^2 - 7x + 3 = (2x - 1)(x - 3), so its roots are 12\frac{1}{2} and 3.

  2. The reciprocals are 2 and 13\frac{1}{3}: sum 73\frac{7}{3}, product 23\frac{2}{3}.

  3. Equation: x2−73x+23=0x^2 - \frac{7}{3}x + \frac{2}{3} = 0, i.e. 3x2−7x+2=03x^2 - 7x + 2 = 0.

Worth noting

Shortcut: reversing the coefficients of ax2+bx+cax^2 + bx + c to cx2+bx+acx^2 + bx + a gives the reciprocal roots. Changing the signs instead gives the NEGATIVES of the roots.

Concept
Transforming roots: reciprocal roots by reversing coefficients
Typical time
120 s
Your time
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The rule this testsQuadratic equations
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Ten questions from Linear and Quadratic Equations, at your own pace.

Practise this chapter →

Ten questions from Linear and Quadratic Equations, at your own pace.