my exam is so hard plz help

Answer:
There are four correct expressions.
Step-by-step explanation:
Four correct expressions:
[tex] {x}^{2} - x - 42[/tex]
[tex] {x}^{2} +6x −7x −42[/tex]
[tex]x(x−7)+6(x−7)[/tex]
[tex] 2x +6x-7x−42[/tex]
Simplify:
[tex] {x}^{2} - x - 42[/tex]
[tex](x+6)(x−7)[/tex]
[tex]x(x−7)+6(x−7)[/tex]
[tex] 2x +6x-7x−42[/tex]
[tex] {x}^{2} −7x+6x−42[/tex]
[tex] {x}^{2} - x - 42[/tex]
Answer:
(x+6)×(x-7)
x(x-7)+6(x-7)
x^2-7x+6x-42
x^2-x-42=0
x^2-(7-6)x-42=0
x^2-7x+6x-42=0
x(x-7)+6(x-7)=0
(x+6).(x-7)=0
x+6=0 is equation one
x-7=0. is equation two
equation one is solve
x+6=0
x=-6
equation two is solve
x-7=0
x=7
therefore, x= -6 and 7