a) 3-`x^2`
= ($\sqrt{3}$+x)($\sqrt{3}$-x)
b) 3-x+`1^2`
= `($\sqrt{3}$-1)^2`
= ($\sqrt{3}$-1)($\sqrt{3}$-1)
c) x+105-4`x^2`
= x+100+5-4`x^2`
= (x+5)-4(`x^2`-25)
= (x+5)-4(`x^2`-`5^2`)
= (x+5)-4(x+5)(x-5)
= (x+5)(1-4x+20)
= (x+5)(21-4x)
d) x+`1^2`-2x-`1^2`
= x-2x
= -1x