$text= $row["text"];
$find = $term;
$result = strpos($text, $find);

substr(string,start,length)

$text= $row["text"];
$find = $term;
$result = strpos($text, $find);
echo substr($text,($result-200>0)?($result-200):0,200)." ".$find." "
.substr($text,$result+strlen($find),200);