Functions Question 594
Question: If $ f:R\to R $ and $ g:R\to R $ are defined by $ f(x)=2x+3 $ and $ g(x)=x^{2}+7 $ , then the values of x such that $ g(f(x))=8 $ are
[EAMCET 2000, 03]
Options:
A) 1, 2
B) -1, 2
C) -1, -2
D) 1, -2
Show Answer
Answer:
Correct Answer: C
Solution:
$ g[ f(x) ]=8 $ or $ g(2x+3)=8 $
Þ $ {{(2x+3)}^{2}}+7=8 $
Þ $ 2x+3=\pm 1 $
Þ $ x=-1,,-2 $ .
BETA
