# SOLUTION: Hi! {{{f(x)= -(4/3)x^2 + 12x}}} Can you prove that: if {{{ a<b<=9/2 }}} so we have {{{f(a)<f(b)}}} Whith that, I'll determine the slope of the function. I tried at fir

Algebra ->  Algebra  -> Functions -> SOLUTION: Hi! {{{f(x)= -(4/3)x^2 + 12x}}} Can you prove that: if {{{ a<b<=9/2 }}} so we have {{{f(a)<f(b)}}} Whith that, I'll determine the slope of the function. I tried at fir      Log On

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 Click here to see ALL problems on Functions Question 412400: Hi! Can you prove that: if so we have Whith that, I'll determine the slope of the function. I tried at first to calculate f(b)-f(a), but I don't know what to do after that... Thank you and sorry for bad English. Answer by richard1234(5390)   (Show Source): You can put this solution on YOUR website!When , the function has a positive slope, since the vertex is at 9/2 and the x^2 coefficient is negative. We can say that the function is *strictly increasing* on this interval, so if , then .