Question Number 208661 by efronzo1 last updated on 20/Jun/24
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Answered by Berbere last updated on 20/Jun/24
$$\mathrm{3}{x}+\mathrm{4}={u}\Rightarrow{dx}=\frac{{du}}{\mathrm{3}} \\ $$$$\int_{\mathrm{10}} ^{\mathrm{25}} {f}\left({u}\right).\frac{{du}}{\mathrm{3}}=\frac{\mathrm{1}}{\mathrm{3}}\left\{.\int_{\mathrm{10}} ^{\mathrm{15}} {f}\left({u}\right){du}+\int_{\mathrm{15}} ^{\mathrm{20}} {f}\left({u}\right){du}+\int_{\mathrm{20}} ^{\mathrm{25}} {f}\left({u}\right){du}\right\} \\ $$$$=\int_{\mathrm{2}} ^{\mathrm{7}} {f}\left({u}\right){du}=\mathrm{5} \\ $$