Giup voi 3 . ( x + 1 ) + 2 . ( x + 2 ) = 5 5 . ( x + 6 ) + 6 . ( x + 1 ) = 47

a) $3(x+1)+2(x+2)=5$

$↔3x+3+2x+4=5$

$↔5x+7=5$

$↔5x=5-7=-2$

$→x=-\dfrac{2}{5}$

b) $5(x+6)+6(x+1)=47$

$↔5x+30+6x+6=47$

$↔11x+36=47$

$↔11x=47-36=11$

$→x=1$