2007-12-06 01:15:12 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
(y² + 8y + 16) - 16 + 18 = 0
(y + 4)² = - 2
(y + 4) = ±√(2 i ²)
y = - 4 ± √2 i
2007-12-06 01:25:51 · answer #1 · answered by Como 7 · 2⤊ 1⤋
y^2 + 8y + 18 = 0?
y^2 + 8y + 16 + 18 - 16 = 0
(y+4)^2 + 2 = 0
(y+4)^2 = -2
{This equation has no real roots.}
y+4 = +/- i sqrt 2
y = -4 +/- i sqrt 2
y = -4 + i sqrt 2 or y = -4 - i sqrt 2
2007-12-06 01:20:47 · answer #2 · answered by Hiker 4 · 1⤊ 1⤋
y^2 + 8y + 18 = 0
so
y^2 + 8y + 16 + 2 = 0
( y + 4 )^2 + 2 = 0
Let i = sqrt(-1), with i^2 = - 1
and sqrt(2) = 1.414
so that (1.414i )^2 = - 2
and
( y + 4 )^2 - (1.414i )^2 = 0
factoring
( y + 4 + 1.414i ) ( y + 4 - 1.414i ) = 0
2007-12-06 01:21:39 · answer #3 · answered by vlee1415 5 · 1⤊ 1⤋
delta=8^2-4*1*18=64-72=-8 delta<0 --->it doesn't have answer
2007-12-06 01:26:17 · answer #4 · answered by Anonymous · 0⤊ 1⤋