Question

помогите сделать 3 задание

Answer 1

$(3y+1)*(3y-1)-(3y-4)^{2}=7$
$(3y+1)*(3y-1)-(3y-4)*(3y-4)=7$
$9y^{2}-1-(9y^{2}-24y+16)=7$
$9y^{2}-1-9y^{2}+24y-16=7$
$24y=7+16+1$
$24y=24$
$y=24:24$
$y=1$