mathrepost
posted by Connie .
Which equation has the complex number 43i as a root?
(1) x^2+6x25=0
(2) x^26x+25=0
(3) x^2+8x25=0
(4) x^28x+25=0
I have no clue how to do it!!!PLEASE HELP!!!Please guide by step by step!!THANKS A LOT~!!!!

mathrepost 
bobpursley
Look at the serds. To get a serd that is negative, you have to have a or c negative. That means only 1 or 3 can be correct. Now, which yields sqrt (b^24ac) to be 6i ?

mathrepost 
Connie
I still don't get it
Respond to this Question
Similar Questions

Calculuscomplex numbers
let z= a+bi be a complex number. it is given that the quotient (zi)/(z1) is purely imaginary. show that z lies on a circle and determine the centre and radius of this circle. OK, here's my working out...( i am using "X" as my times … 
math
Which equation has the complex number 43i as a root? 
math
Which equation has the complex number 43i as a root? 
Math
2(5x + 1) = 3(3x + 7) a) x = 19 b) x = 20 c) x = 21 Can you please explain it step by step please? 
Physics
I'm trying to rearange this 0 = Xo + 2^1 a t^2 for t I've been told that it is (a^1 2x)^(2^1) but I do not see how please show me step by step how you get that 0  Xo = Xo  Xo + 2^1 a t^2 (Xo = 2^1 a t^2) a^1 2 (a^1 (2Xo) … 
mathfunctions starting
3f(x4)=x^2 i have no clue what to do with the 3 in front of the f. please explain step by step as to how to do this question the answer in the back is 3x^2+24x48 
Math
How do you do this Simultaneous Equation? 
Physics
Can someone please show me step by step how to normalize e^5x in the interval (0, infinity)? 
TRIGONOMETRY
Can someone please show me step by step how to calculate the modulus and the argument for these complex numbers? 
algebra
help me please im confused Consider the quadratic expression X^2 + 4x + c = 0. For what range of values does the equation have two complex roots?