Quantitative Aptitude Ques 921
Question: Thrice the square of a natural number decreased by four times the number is equal to 50 more than the number. The number is
Options:
A) 4
B) 5
C) 10
D) 6
Show Answer
Answer:
Correct Answer: B
Solution:
- Let the number be x. Then, $ 3x^{2}-4x=x+50 $
$ \Rightarrow $ $ 3x^{2}-5x-50=0 $
$ \Rightarrow $ $ 3x^{2}-15x+10x-50=0 $
$ \Rightarrow $ $ 3x(x-5)-10(x-5)=0 $
$ \Rightarrow $ $ (3x-10)(x-5)=0 $
$ \Rightarrow $ $ x=\frac{10}{3},5 $ But the number is natural number
$ \therefore $ $ x=5 $
BETA
