问题
解答题
(1)解方程:x2+3x+1=0; (2)计算:(3
|
答案
(1)a=1,b=3,c=1,
∴x=
=-3± 9-4×1×1 2×1
,-3± 5 2
∴x1 =
,-3+ 5 2
x2 =
.-3- 5 2
(2)原式=(9
+2
-22
)÷42
=82
÷42
=2.2
(1)解方程:x2+3x+1=0; (2)计算:(3
|
(1)a=1,b=3,c=1,
∴x=
=-3± 9-4×1×1 2×1
,-3± 5 2
∴x1 =
,-3+ 5 2
x2 =
.-3- 5 2
(2)原式=(9
+2
-22
)÷42
=82
÷42
=2.2