Question
Quantitative Aptitude Question on Equations
If 2x = 364 ,then x2+x+1 = ?
6
7
8
5
7
Solution
To solve the equation f⋅2x=364 ,we first need to find the value of 364
364 = 4 (since 43=64)
Rearranging the equation:
f⋅2x= 4
Assuming f is a constant that we will solve for later, we can divide both sides by f:
⇒2x=f4
Take the logarithm: Taking the logarithm base 2 on both sides:
x=log2(f4)
Next, we need to find x2+x+1
Calculate x:
x=log2(2)2−log2(f)=2−log2(f)
Substituting into x2+x+1
x2=(2−log2(f))2=4−4log2(f)+(log2(f))2
Now add x and 1:
x2+x+1=(4−log2(f)+(log2(f))2)+(2−log2(f))+1
=4+2+1−4log2(f)−log2(f)+(log2(f))2
=7−5log2(f)+(log2(f))2
Without knowing the exact value of f, we cannot simplify further to arrive at one of the answer choices directly.
If you meant f=1, then:
log2(1)=0
x=2
x2+x+1=22+2+1=4+2+1=7
So the correct option is (B):7