NIMCET 2015 — Mathematics PYQ
NIMCET | Mathematics | 2015If x,y, and z are three consecutive positive integers, then log(1+xz) is:
Choose the correct answer:
- A.
logy
- B.
log2y
- C.
log(2y)
- D.
2log(y)
(Correct Answer)
2log(y)
Explanation
Since x,y, and z are three consecutive positive integers, we can write them in terms of y:
x=y−1
z=y+1
Now, substitute these into the expression:
1+xz=1+(y−1)(y+1)
Apply the algebraic identity (a−b)(a+b)=a2−b2:
1+xz=1+(y2−1)
1+xz=y2
Now, take the logarithm of the expression:
log(1+xz)=log(y2)
Using the property of logarithms log(an)=nloga:
log(y2)=2logy
Correct Option: (d)
Explanation
Since x,y, and z are three consecutive positive integers, we can write them in terms of y:
x=y−1
z=y+1
Now, substitute these into the expression:
1+xz=1+(y−1)(y+1)
Apply the algebraic identity (a−b)(a+b)=a2−b2:
1+xz=1+(y2−1)
1+xz=y2
Now, take the logarithm of the expression:
log(1+xz)=log(y2)
Using the property of logarithms log(an)=nloga:
log(y2)=2logy
Correct Option: (d)