Question #9a361
1 Answer
Dec 13, 2017
Explanation:
#"complex roots occur as "color(blue)"conjugate pairs"#
#x=1-2i" is a root "rArrx=1+2i" is also a root"#
#x=3i" is a root "rArrx=-3i" is also a root"#
#rArrp(x)=(x-3i)(x+3i)(x-1+2i)(x-1-2i)#
#color(white)(rArrp(x))=(x^2-9i^2)((x-1)^2-4i^2)#
#•color(white)(x)[i^2=(sqrt(-1))^2=-1]#
#=(x^2+9)(x^2-2x+1+4)#
#=(x^2+9)(x^2-2x+5)#
#=x^4-2x^3+5x^2+9x^2-18x+45#
#=x^4-2x^3+14x^2-18x+45#