Can you solve this?

Algebra Level 1

If the value of

2 1998 2 1997 2 1996 + 2 1995 = k 2 1995 2^{1998} - 2^{1997} - 2^{1996} + 2^{1995} = k \cdot 2^{1995}

What is the value of k ? k?


The answer is 3.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

9 solutions

Shubhendra Singh
Nov 13, 2014

The given expression can be simplified as

2 1995 ( 2 3 2 2 2 + 1 ) = k × 2 1995 2^{1995}(2^{3}-2^{2}-2+1)=k \times 2^{1995}

k = 8 4 2 + 1 k=8-4-2+1

k = 3 k=3

really clear :-)

Ellen Yan - 6 years, 4 months ago

2 1998 2 1997 2 1996 + 2 1995 = k × 2 1995 2^{1998}-2 ^{1997}-2^{1996}+2^{1995}=k\times 2^{1995} Factoring the L.H.S, We get: 2 1995 ( 2 3 2 2 2 + 1 ) = k × 2 1995 2^{1995}(2^3-2^2-2+1)=k\times 2^{1995} Cancelling out the 2 1995 s 2^{1995}s from L.H.S and R.H.S, we get: 2 3 2 2 2 + 1 = k 2^3-2^2-2+1=k Solving,we get: 2 3 2 2 2 + 1 = k 2^3-2^2-2+1=k k = 8 4 2 + 1 = 4 2 + 1 = 2 + 1 = 3 k=8-4-2+1=4-2+1=2+1=\boxed{3}

Daniel Dominguez
Nov 29, 2014

If 2 n + 1 2 n = 2 n 2^{n+1}- 2^{n} = 2^{n} then:

2 1998 2 1997 = 2 1997 2^{1998} - 2^{1997} = 2^{1997}

2 1997 2 1996 = 2 1996 2^{1997} - 2^{1996} = 2^{1996}

If 2 n + 1 + 2 n = 2 n × 3 2^{n+1} + 2^{n} = 2^{n} \times 3 then:

2 1996 + 2 1995 = 2 1995 × 3 2^{1996} + 2^{1995} = 2^{1995} \times 3

Therefore k is 3

2 1998 2 1997 2 1996 + 2 1995 = k 2 1995 2^{ 1998 }-2^{ 1997 }-2^{ 1996 }+2^{ 1995 }=k\cdot 2^{ 1995 }

We can do this:

( 2 1998 2 1997 ) 2 1996 + 2 1995 = k 2 1995 \left( 2^{ 1998 }-2^{ 1997 } \right) -2^{ 1996 }+2^{ 1995 }=k\cdot 2^{ 1995 }

We know that:

2 n + 1 2 n = 2 2 n 2 n = 2 n + 2 n 2 n = 2 n 2^{ n+1 }-{ 2 }^{ n }=2\cdot { 2 }^{ n }-{ 2 }^{ n }={ 2 }^{ n }+{ 2 }^{ n }{ -2 }^{ n }={ 2 }^{ n }

So:

( 2 1998 2 1997 ) 2 1996 + 2 1995 = k 2 1995 \left( 2^{ 1998 }-2^{ 1997 } \right) -2^{ 1996 }+2^{ 1995 }=k\cdot 2^{ 1995 }

2 1997 2 1996 + 2 1995 = k 2 1995 2^{ 1997 }-{ 2 }^{ 1996 }+{ 2 }^{ 1995 }=k\cdot 2^{ 1995 }

For the same principle:

( 2 1997 2 1996 ) + 2 1995 = 2 1996 + 2 1995 \left( { 2 }^{ 1997 }-{ 2 }^{ 1996 } \right) +{ 2 }^{ 1995 }={ 2 }^{ 1996 }{ +2 }^{ 1995 }

Simplifying:

2 1996 + 2 1995 = k 2 1995 { 2 }^{ 1996 }+{ 2 }^{ 1995 }=k\cdot { 2 }^{ 1995 }

2 2 1995 + 2 1995 = k 2 1995 2\cdot { 2 }^{ 1995 }+{ 2 }^{ 1995 }=k\cdot { 2 }^{ 1995 }

2 1995 + 2 1995 + 2 1995 = k 2 1995 { 2 }^{ 1995 }+{ 2 }^{ 1995 }+{ 2 }^{ 1995 }=k\cdot { 2 }^{ 1995 }

3 2 1995 = k 2 1995 3\cdot { 2 }^{ 1995 }=k\cdot { 2 }^{ 1995 }

k = 3 \boxed{k=3}

Nain Tara
Dec 25, 2014

2^1997 - 2^1996 + 2^1995 = k 2 ^1995 2 ^1995 ( 2^3 - 2^2 - 2 + 1 ) = k 2 ^1995 3 * 2 ^1995 = k 2 ^1995, k=3

Anna Anant
Nov 26, 2014

2^1997 - 2^1996 + 2^1995 = k 2 ^1995 2 ^1995 ( 2^3 - 2^2 - 2 + 1 ) = k 2 ^1995 3 * 2 ^1995 = k 2 ^1995, k=3

Cm Sharif
Nov 22, 2014

The given expression can be simplified

2^{1995}.2^{3}-2^{1995}.2^{2}-2^{1995}.2^{1}+2^{1995}=k.2^{1995}

2^{1995}(2^{3}-2^{2}-2^{1}+1)=k.2^{1995}

(8-4-2+1)=k

k=3

Siva Prasad Sodam
Nov 18, 2014

2^{1995} (2^{3}-2^{2}-2^{1}+1)=K2^{1995} 8-4-2+1=K K=3

Samad Badi
Nov 13, 2014

Divide All terms by 2^1995 and take denominator to numerator to solve!!

Please provide a complete solution. @Samad Badi

Anuj Shikarkhane - 6 years, 7 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...