Question

解方程：2y²+8y-1=0

Answer 1

∵a=2，b=8，c=-1
△=8²-4×2×（-1）=72
y=

-8± 72

2×2

=

-4±3 2

2

∴y1=

-4+3 2

2

，y2=

-4-3 2

2