=
2^x-2^x-2^-2=3(2^13)
2^x(1-1/4)=3(2^13)
2^x(3/4)=3(2^13)
2^x=2^13*2^2) (cross multiply 3/4. it gives you 4 (2^2) in the right part)
2^x=2^15
x=15
hope it helps....
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Source: Beat The GMAT — Problem Solving |
This is very simple question ,
Answer is 15
How do we get 15 , there are several ways , but by using logic u can get it without doing any calculations
In the given equations , look at the Right side , there is a 3 and a some power of 2 , this equals the left side , where there are two powers of 2 liked by -
If u look carefully at Left hand side you see that 2^(x-2) is nothing but 2^x/4 [ 2^-a = 1/2^a and 2^a/2^b = 2^a-b)
that means on the left the second power is 1/4 th the first so we have
3/4 (2^X) = 3*2^13 ------> 2^x = 4*2^13 = 2^2*2^13 = 2^15
X = 15
Answer is 15
How do we get 15 , there are several ways , but by using logic u can get it without doing any calculations
In the given equations , look at the Right side , there is a 3 and a some power of 2 , this equals the left side , where there are two powers of 2 liked by -
If u look carefully at Left hand side you see that 2^(x-2) is nothing but 2^x/4 [ 2^-a = 1/2^a and 2^a/2^b = 2^a-b)
that means on the left the second power is 1/4 th the first so we have
3/4 (2^X) = 3*2^13 ------> 2^x = 4*2^13 = 2^2*2^13 = 2^15
X = 15
Yes.simple algebra
If you are not doing silly mistake you are ok here
Btw, I am amazed to see the position of this Q
No 16 and not in no 3 or 4
If you are not doing silly mistake you are ok here
Btw, I am amazed to see the position of this Q
No 16 and not in no 3 or 4
