Question: Which of the following functions is strictly decreasing for $\displaystyle x\in\Re$?

(a)$\displaystyle f(x)=x^2$

(b)$\displaystyle f(x)=-x$

(c)$\displaystyle f(x)=\sqrt{x}$

(d)$\displaystyle f(x)=2-x^2$

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- Dec 9th 2009, 02:50 PMibnashrafstrictly decreasing
Question: Which of the following functions is strictly decreasing for $\displaystyle x\in\Re$?

(a)$\displaystyle f(x)=x^2$

(b)$\displaystyle f(x)=-x$

(c)$\displaystyle f(x)=\sqrt{x}$

(d)$\displaystyle f(x)=2-x^2$ - Dec 9th 2009, 03:03 PMskeeter
- Dec 9th 2009, 06:35 PMmillerst
The answer is (b), $\displaystyle f(x)=-x $... but if you don't understand this I think you need to invest time into understanding the graphs and what it means to have a decreasing function...