Answer:
Look below
Step-by-step explanation:
[tex]Note: i=\sqrt{-1}[/tex]
18. Start by factoring out a 5 on the left side:
[tex]5(x^2+25)=0[/tex]
Then, divide both sides by 5:
[tex]x^2+25=0[/tex]
Subtract 25 from both sides:
[tex]x^2=-25[/tex]
Take the square root of both sides:
[tex]x=-\sqrt{-25} \ or\ x=-\sqrt{25}[/tex]
[tex]x=-5i, 5i[/tex]
20. Start by adding 16 to both sides:
[tex]-x^2=16[/tex]
Divide both sides by -1:
[tex]x^2=-16[/tex]
Take the square root of both sides:
[tex]x=-\sqrt{16} \ or\ -\sqrt{-16}[/tex]
[tex]x=-4i, 4i[/tex]
22. Start by subtracting 96 from both sides:
[tex]8x^2=-96[/tex]
Divide both sides by 8:
[tex]x^2=-12[/tex]
Take the square root of both sides:
[tex]x=\sqrt{-12}\ or\ -\sqrt{-12}[/tex]
[tex]x=-2i\sqrt{3}, 2i\sqrt{3}[/tex]
