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Mathematics 20 Online
OpenStudy (howard-wolowitz):

ONE QUESTION .. WILL MEDAL!

OpenStudy (howard-wolowitz):

I really need help on this question ^

OpenStudy (jdoe0001):

I think they meant to "use" f(x) in the rational expression thus

OpenStudy (howard-wolowitz):

well i cant get anyone who actually knows how to do this question so I hope you do dude its a hard one

OpenStudy (anonymous):

no. its derivative

OpenStudy (jdoe0001):

\(\bf \cfrac{f({\color{brown}{ a}}+h)-f({\color{brown}{ a}})}{h}\qquad f({\color{brown}{ x}})={\color{brown}{ x}}^2+5{\color{brown}{ x}}\quad or\quad f({\color{brown}{ a}})={\color{brown}{ a}}^2+5{\color{brown}{ a}} \\ \quad \\ f({\color{blue}{ a+h}})=({\color{blue}{ a+h}})^2+5({\color{blue}{ a+h}})\qquad thus \\ \quad \\ \cfrac{f({\color{brown}{ a}}+h)-f({\color{brown}{ a}})}{h}\implies \cfrac{({\color{blue}{ a+h}})^2+5({\color{blue}{ a+h}})\quad -\quad (a^2+5a)}{h}\)

OpenStudy (anonymous):

recal that \[limx rightarrowh={ h(a+h)+f(a)}/h\]

OpenStudy (howard-wolowitz):

hmm ok

OpenStudy (anonymous):

very correct @jdoe0001

OpenStudy (howard-wolowitz):

that looks like C

OpenStudy (jdoe0001):

expand the squared expression, and cancel out what you can, see what you end up with

OpenStudy (howard-wolowitz):

ok one sec

OpenStudy (howard-wolowitz):

so what exactly am i solving.. sorry

OpenStudy (jdoe0001):

\(\bf \cfrac{f({\color{brown}{ a}}+h)-f({\color{brown}{ a}})}{h}\qquad f({\color{brown}{ x}})={\color{brown}{ x}}^2+5{\color{brown}{ x}}\quad or\quad f({\color{brown}{ a}})={\color{brown}{ a}}^2+5{\color{brown}{ a}} \\ \quad \\ f({\color{blue}{ a+h}})=({\color{blue}{ a+h}})^2+5({\color{blue}{ a+h}})\qquad thus \\ \quad \\ \cfrac{f({\color{brown}{ a}}+h)-f({\color{brown}{ a}})}{h}\implies \cfrac{({\color{blue}{ a+h}})^2+5({\color{blue}{ a+h}})\quad -\quad (a^2+5a)}{h}\) I think the confusing part is that, they used "x" on the f(x) function and they use f(a) in the part where it is going to be used but in short, you can just replace the "x" for "a" and use \(\bf f({\color{brown}{ a}})={\color{brown}{ a}}^2+5{\color{brown}{ a}}\)

OpenStudy (howard-wolowitz):

dang.. ok one sec

OpenStudy (howard-wolowitz):

ok um one more sec

OpenStudy (jdoe0001):

what does the binomial \(\large \bf (a+h)^2\) give you?

OpenStudy (howard-wolowitz):

almost done one sec

OpenStudy (jdoe0001):

k

OpenStudy (howard-wolowitz):

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