Answer :
1. (x+2)(x+5)
We have a formula (a+b) ( c+d)= ac+ad+bc+bd
(x+2)(x+5)= x^2+5x+2x+10= x^2+7x+10
2. By using same formula,
(x-4)(x+9)= x^2+9x+(-4x)+(-4*9)= x^2+9x-4x+(-36)= x^2+5x-36
We have a formula (a+b) ( c+d)= ac+ad+bc+bd
(x+2)(x+5)= x^2+5x+2x+10= x^2+7x+10
2. By using same formula,
(x-4)(x+9)= x^2+9x+(-4x)+(-4*9)= x^2+9x-4x+(-36)= x^2+5x-36