Question

I seriously don't know.

Answer 1

1)
(x+3)(x+5)=
x*x+x*5+3*x+3*5=
x^2+5x+3x+15=
x^2+8x+15
2)
(x+3)(x-5)=
x*x+x*(-5)+3*x+3*(-5)=
x^2-5x+3x-15=
x^2-2x-15
3)
(x-3)(x-5)=
x*x+x*(-5)+(-3)*x+(-3)*(-5)=
x^2-5x-3x+15=
x^2-8x+15
4)
(2x+4)(x-7)=
(2x)*x+(2x)*(-7)+4*x+4*(-7)=
2x^2-14x+4x-28=
2x^2-10x-28

Answer 2

#1.

$(x+3)(x+5)$
$x^2+5x+3x+15$
$x^2+8x+15$

#2.

$(x+3)(x-5)$
$x^2-5x+3x-15$
$x^2-2x-15$

#3.

$(x-3)(x-5)$
$x^2-5x-3x+15$
$x^2-8x+15$

#4.

$(2x+4)(x-7)$
$2x^2-14x+4x-28$
$2x^2-10x-28$


Hope I've Helped!