${a)}$ ${720:[41-(2x-5)]=2^{3}.5}$
${720:[41-(2x-5)]=8.5}$
${720:[41-(2x-5)]=40}$
${41-(2x-5)= 720 : 40 }$
${41-(2x-5) = 18}$
${2x-5=41-18}$
${2x-5=23}$
${2x=28}$
${x=14}$
Vậy ${x=14}$
${b)}$ ${6.(x+11)-7.(2-x)=26}$
${6x+66-14+7x=26}$
${(6x+7x)+(66-14)=26}$
${13x + 52 = 26 }$
${13x = 26 - 52 }$
${13x = -26}$
${x=-26:13}$
${x=-2}$
Vậy ${x=-2}$
${c)}$ $(7x-11)^{2}$ = $2^{5}$ . $5^{2}$ + ${100}$
$(7x-11)^{2}$ = ${32 . 25 +100}$
$(7x-11)^{2}$ = ${900}$
$(7x-11)^{2}$ = $30^{2}$
${7x-11=30}$
${7x=41}$
${x = \frac{41}{7} }$
Vậy${x = \frac{41}{7} }$
$\text{HỌC TỐT!}$
