Question Number 143507 by Billy last updated on 15/Jun/21
$$\mathrm{10}\sqrt{\mathrm{20}}+\mathrm{13}\sqrt{\mathrm{45}} \\ $$
Answered by qaz last updated on 15/Jun/21
$$\mathrm{10}\sqrt{\mathrm{20}}+\mathrm{13}\sqrt{\mathrm{45}} \\ $$$$=\mathrm{10}×\mathrm{2}\sqrt{\mathrm{5}}+\mathrm{13}×\mathrm{3}\sqrt{\mathrm{5}} \\ $$$$=\left(\mathrm{20}+\mathrm{39}\right)\sqrt{\mathrm{5}} \\ $$$$=\mathrm{59}\sqrt{\mathrm{5}} \\ $$