Factor out the variable that is raised 
to the smaller exponent 

-5x-2 + x2

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When you factor xp out of

axp + bxq 

you get

xp(a + bxq-p)

So when you factor x-2 out of

-5x-2 + x2 

you get

x-2(-5 + x2-(-2))

Then you simplify a bit

x-2(-5 + x2+2)

x-2(-5 + x4)

x-2(x4 - 5)

Edwin