Loading [MathJax]/jax/output/SVG/jax.js
 
+0  
 
0
335
1
avatar

Given that x=2 is a root of p(x)=x^4-3x^3-18x^2+90x-100, find the other roots (real and nonreal).

 Jan 9, 2022
 #1
avatar+26 
0

By synthetic division, we get that p(x)=(x2)(x3x220x+50). By Rational Root Theorem, the possible roots of x3x220x+50 are ±1,±2,±5,±10,±25, and ±50. Testing values, we get that x=5 works, so by synthetic division, we get that p(x)=(x2)(x+5)(x26x+10).

 

By the quadratic formula, the roots of x26x+10 are 6±(6)2411021=6±2i2=3±i. Thus, the roots of p(x) are 5,2,3+i,and 3i.

 Jan 10, 2022

2 Online Users

avatar