Question 155328

Note: i think  you forgot to put an x after (m+3)
{{{ax^2+bx+c}}} has equal roots when {{{b^2-4ac=0}}}

{{{(m+1)x^2+2(m+3)x+(m+8)=0}}} has equal roots when
{{{(2(m+3))^2-4(m+1)(m+8)=0}}}
then
{{{(2m+6)^2-4(m^2+9m+8)=0}}}
then
{{{4m^2+24m+36-4m^2-36m-32=0}}}
then
{{{-12m+4=0}}}
then
{{{m=4/12=1/3}}}
Answer:m=3