Poor y

Algebra Level 2

If x , y , z 1 x, y, z \neq 1 are three consecutive natural numbers, then the value of l o g ( 1 + x z ) log(1 + xz) is

l o g x y z log xyz 2 l o g y 2 log y l o g y log y 3 l o g y 3 log y

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5 solutions

Since x , y x, y and z z are consecutive natural numbers, then x = y 1 , z = y + 1 x=y-1, z=y+1 .

1 + x z 1+xz , therefore, is equal to 1 + ( y 1 ) ( y + 1 ) 1 + y 2 1 y 2 1+(y-1)(y+1) \Rightarrow 1+y^2-1 \Rightarrow y^2

l o g ( 1 + x z ) = l o g ( y 2 ) = 2 l o g ( y ) log(1+xz)=log(y^2)=\boxed{2log(y)}

Sameh Rehan
Apr 14, 2014

log(1+xz)=log(1+(y-1)(y+1))=log(y*y)=2log(y) : x,y,z consecutive natural numbers

Uahbid Dey
May 2, 2014

The numbers are x, y = x+1 and z = y+1 = x+2 now, log(1+xz) = log{1+x(x+2)} = log(1+x²+2x) = log(1²+x²+2.x.1) = log(1+x)² = 2 log(1+x) = 2logy

K Vardhan Reddy
Apr 24, 2014

2logy is solution

log(1+xz) =log(1+x(x+2)) =log(1+x^{2} +2x) =log((1+x)^{2})) =2log(1+x) =2log(y)

Raghu Shankar - 7 years, 1 month ago
Denton Young
Nov 21, 2016

Since it didn't specify values, we can take any values we like. Let x = 9, y = 10, z= 11. Then log (1 + xz) = log (100) = 2 and log y = log 10 = 1. 2 = 2(1).

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