Question

Помогите, пожалуйста

1) (2-x)(8-x)<0

2) (1-x)(7-x)>0

3) (x-2)(5+x)>0

Answer 1

1) 16-2x-8x+x²<0
x²-10x+16=0
D= b²-4ac = 100-64= 36
x1= -b-√D
-------- = 10-6
2a. ------ = 2
2

x2= -b+√D
-------- = 10+6
2a. ------ = 8
2
+ - +
——•——•———›
2 8
(-∞;2)€(8;∞)

2) 7-x-7x+x²>0
x²-8x+7=0
D=b²-4ac= 64-28=36
x1= -b-√D = 8-6 =1
-------- -----
2a. 2

x2= -b+√D
-------- = 8+6
2a. ------ = 7
2
+. - +
———•——•——›
1 7
(-∞;1)€(7;∞)

3)5x+x²-10-2x>0
x²+3x-10=0
D=b²-4ac= 9+40=49
x1= -b-√D
-------- = -3-7
2a. ------ = -5
2
x2= -b+√D
-------- = -3+7
2a. ------ = 2
2
+ - +
———•————•———›
-5 2
(-∞;-5)€(2;∞)