Well, this is easy. You need to think of two numbers that when you add them, the sum is 10 and when you multiply them, the product is 9.
so the numbers are 1 and 9.
1+9=10; 1x9=9.. since both b and c are positive.. the signs of the roots are also positive.
(x+1)(x+9).. and if we equate them, it would be:
x+1=0 ; x+9=0..we transpose the digits to get x..
x=-1 : x=-9 so therefore, the roots are -1, -9