Question
A and B solved a quadratic equation. In solving it , A made a mistake in the constant term and obtained the roots as 5, -3 while B made a mistake in the coefficient of x and obtained the roots as 1, -3. The correct roots of the equation are
Answer: Option B
:
B
Using the reverse gear approach
If the equation is ax2+bx+c=0.
A's mistake will be in "c”, hence sum of roots = −ba=2.....(i) will be the correct value. Product of roots = ca will be wrong in this case
B's mistake will be in "b”, hence product of roots =ca=−3......(ii) will yield the correct value. In this case, sum of roots value = −ba will be wrong
Look in the answer options for the pair of roots which satisfy sum of roots = 2 and product of roots = -3. Answer is option (b).
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:
B
Using the reverse gear approach
If the equation is ax2+bx+c=0.
A's mistake will be in "c”, hence sum of roots = −ba=2.....(i) will be the correct value. Product of roots = ca will be wrong in this case
B's mistake will be in "b”, hence product of roots =ca=−3......(ii) will yield the correct value. In this case, sum of roots value = −ba will be wrong
Look in the answer options for the pair of roots which satisfy sum of roots = 2 and product of roots = -3. Answer is option (b).
Was this answer helpful ?
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