Question Number 96052 by 174 last updated on 29/May/20
Answered by john santu last updated on 29/May/20
$$\left(\mathrm{a}−\mathrm{3}\right)\left(\mathrm{a}+\mathrm{10}\right)\:=\:\mathrm{a}^{\mathrm{2}} +\mathrm{7a}−\mathrm{30} \\ $$$$=\mathrm{13}−\mathrm{30}\:=\:−\mathrm{17}\: \\ $$$$\left(\mathrm{a}+\mathrm{2}\right)\left(\mathrm{a}+\mathrm{5}\right)=\mathrm{a}^{\mathrm{2}} +\mathrm{7a}+\mathrm{10}=\mathrm{23} \\ $$$$\mathrm{then}\:=\:\left(−\mathrm{17}\right)×\left(\mathrm{23}\right)\:=−\mathrm{391} \\ $$