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Question

Quantitative Aptitude Question on Equations

If 2x2^x = 643\sqrt[3]{64} ,then x2+x+1x^2 + x + 1 = ?

A

6

B

7

C

8

D

5

Answer

7

Explanation

Solution

To solve the equation ff2x2^x=643\sqrt[3]{64} ,we first need to find the value of 643\sqrt[3]{64}
643\sqrt[3]{64} = 4 (since 43=64)
Rearranging the equation:
ff2x2^x= 4
Assuming ff is a constant that we will solve for later, we can divide both sides by ff:
2x=4f2^x=\frac{4}{f}
Take the logarithm: Taking the logarithm base 2 on both sides:
x=log2(4f)x=\log_2(\frac{4}{f})
Next, we need to find x2+x+1x^2+x+1
Calculate xx:
x=log2(2)2log2(f)=2log2(f)x=\log_2(2)^2-log_2(f)=2-log_2(f)
Substituting into x2+x+1x^2+x+1
x2=(2log2(f))2=44log2(f)+(log2(f))2x^2=(2-log_2(f))^2=4-4log_2(f)+(log_2(f))^2
Now add xx and 1:
x2+x+1=(4log2(f)+(log2(f))2)+(2log2(f))+1x^2+x+1=(4-\log_2(f)+(log_2(f))^2)+(2-log_2(f))+1
=4+2+14log2(f)log2(f)+(log2(f))2=4+2+1-4log_2(f)-log_2(f)+(log_2(f))^2
=75log2(f)+(log2(f))2=7-5log_2(f)+(log_2(f))^2
Without knowing the exact value of ff, we cannot simplify further to arrive at one of the answer choices directly.
If you meant ff=1, then:
log2(1)=0\log_2(1)=0
x=2x=2
x2+x+1=22+2+1=4+2+1=7x^2+x+1=2^2+2+1=4+2+1=7
So the correct option is (B):7