



 
Hi Abdiwahid, Suppose the root is $r$ then the equation can be written \[(x  r)(x  r) = 0\] so \[x^2+2ax+4x+9a = (x  r)(x  r).\] Expand the right side and simplify. This equation is true for all values of $x$ so what does this tell you about $a$ and $r$ when $x = 0?$ This gives you one equation in $a$ and $r.$ Find another equation relating $a$ and $r.$ Solve the two equations for $a.$ Penny  


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