Posted by mikey on .
1)Solve and write in standard form:
4x^24x+21=0
2)Find the standard form of the complex number.
8(cos pi/2 + i sin pi/2)
Thanks everyone!

trigonometry 
Reiny,
x = (4 ± √(16  16(21)) )/8
= (4 ± √320)/8
= (4 ± 8√5)/8
= 1/2 ± i√5
x = 1/2 + i√5 or x = 1/2  i√5
2)
8(cos π/2 + i sin π/2)
= 8(√2/2 + i √2/2)
= 4√2 + i (4√2)