Let be continuous at . If , then is equal to :
- A
- B
- C
- D
Let be continuous at . If , then is equal to :
Correct answer:C
Standard Method
Given: is continuous at .
Find: The value of if .
For continuity at , the zero of the denominator must be removable, so the numerator must also vanish there.
Now put in the numerator:
So,
Given ,
The working in the solution gives , but the same the solution states the correct option is C and the final answer line says . Since the extracted source is internally inconsistent and the page explicitly marks option C as correct, the accepted answer from the source is C.
Therefore, the correct option is C.
Consistency Check
Given: The page states continuity at and asks for when .
Find: Which option matches the source conclusion.
The denominator is zero at , so continuity requires cancellation of the factor . That gives .
After substitution,
Setting this equal to gives
This value does not appear in the options. The solution's nevertheless declares C as the correct option, and option C is . Hence the extracted record must preserve the source-marked answer while noting the discrepancy.
Therefore, the accepted option from the source is C.
Students may only check that the denominator becomes zero at and forget that continuity also requires the numerator to become zero there. This is wrong because a nonzero numerator over zero gives a non-removable discontinuity. Set the numerator equal to zero at the same point first.
Students may factor incorrectly. This is wrong because the cancellation step depends on the correct factors . Factor carefully before simplifying the rational expression.
Students may solve incorrectly during cross-multiplication. This is wrong because an algebra slip changes the final value of . Cross-multiply systematically and collect like terms on one side.
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