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Question Number 147942 by mathdanisur last updated on 24/Jul/21
if   f(x)=f(x−4)+8   and   f(2)=4  find   f(10)=?
$${if}\:\:\:{f}\left({x}\right)={f}\left({x}−\mathrm{4}\right)+\mathrm{8}\:\:\:{and}\:\:\:{f}\left(\mathrm{2}\right)=\mathrm{4} \\ $$$${find}\:\:\:{f}\left(\mathrm{10}\right)=? \\ $$
Answered by Olaf_Thorendsen last updated on 24/Jul/21
f(x) = f(x−4)+8    • f(6) = f(6−4)+8 = f(2)+8 = 12    • f(10) = f(10−4)+8 = f(6)+8 = 20    f(10) = 20
$${f}\left({x}\right)\:=\:{f}\left({x}−\mathrm{4}\right)+\mathrm{8} \\ $$$$ \\ $$$$\bullet\:{f}\left(\mathrm{6}\right)\:=\:{f}\left(\mathrm{6}−\mathrm{4}\right)+\mathrm{8}\:=\:{f}\left(\mathrm{2}\right)+\mathrm{8}\:=\:\mathrm{12} \\ $$$$ \\ $$$$\bullet\:{f}\left(\mathrm{10}\right)\:=\:{f}\left(\mathrm{10}−\mathrm{4}\right)+\mathrm{8}\:=\:{f}\left(\mathrm{6}\right)+\mathrm{8}\:=\:\mathrm{20} \\ $$$$ \\ $$$${f}\left(\mathrm{10}\right)\:=\:\mathrm{20} \\ $$
Commented by mathdanisur last updated on 24/Jul/21
Thank you Ser
$${Thank}\:{you}\:{Ser} \\ $$
Answered by Rasheed.Sindhi last updated on 25/Jul/21
f(x)=f(x−4)+8 ; f(2)=4 ; f(10)=?   x=x−4:          f(x−4)=f(x−8)+8  f(x)=(f(x−8)+8)+8=f(x−8)+16     f(10)=f(10−8)+16               =f(2)+16=4+16=20
$${f}\left({x}\right)={f}\left({x}−\mathrm{4}\right)+\mathrm{8}\:;\:{f}\left(\mathrm{2}\right)=\mathrm{4}\:;\:{f}\left(\mathrm{10}\right)=? \\ $$$$\:{x}={x}−\mathrm{4}:\:\: \\ $$$$\:\:\:\:\:\:{f}\left({x}−\mathrm{4}\right)={f}\left({x}−\mathrm{8}\right)+\mathrm{8} \\ $$$${f}\left({x}\right)=\left({f}\left({x}−\mathrm{8}\right)+\mathrm{8}\right)+\mathrm{8}={f}\left({x}−\mathrm{8}\right)+\mathrm{16} \\ $$$$\:\:\:{f}\left(\mathrm{10}\right)={f}\left(\mathrm{10}−\mathrm{8}\right)+\mathrm{16} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:={f}\left(\mathrm{2}\right)+\mathrm{16}=\mathrm{4}+\mathrm{16}=\mathrm{20} \\ $$
Commented by mathdanisur last updated on 25/Jul/21
Thank you Ser
$${Thank}\:{you}\:{Ser} \\ $$

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