SOLUTION: Hi. I just started learning complex numbers and I need help understanding how to do the following problems please=] #1) 2x^2+9=-41 #2) 3s^2-1=7s^2 #3) -6(u + 5)

Question 193128: Hi. I just started learning complex numbers and I need help understanding how
to do the following problems please=]

#1) 2x^2+9=-41

#2) 3s^2-1=7s^2

#3) -6(u + 5)^2=120

#4) (2 - 6i)-(10 + 4i)
Thank You so much,
Lynda=]
Answer by RAY100(1637) (Show Source): You can put this solution on YOUR website!
remember sqrt (-1)=i
1) 2x^2+9=-41
2x^2=-50
x^2=-25
x=+/- 5i
2)3s^2-1=7s^2
-1=4s^2
-(1/4) =s^2
+/- (1/2) i =s
3) -6(u+5)^2=120
(u+5)^2=-20
u^2+10u+25=-20
u^2+10u+45=0
solve using quadratic eqn
a=1,,,b=10,,,,c=45
u= (-10 +/-sqrt ((10)^2-4(1)(45)))/2(1)
u= (-10+/-sqrt (100-180))/2
u= (-10+/-sqrt(-80))/2
u= (10+/-8.94i)/2
u=5+/-4.47i
4) (2-6i)-(10+4i)
(-8)-10i
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