Question

1)(0,5-2х)(2х+0,5)+(0,7+х)2=0,92-0,1х

2)х2-х+3/4=0

3)-0,04+х2=0

4)1/6х2-х+3/4=0

5)х2+3,2х-9=0

 

 

 

 

 

 

 

 

Answer 1

1)(0,5-2х)(2х+0,5)+(0,7+х)^2=0,92-0,1х

0.25-4x^2+0.49+1.4x+x^2-0.92+0.1x=0 |*100

25-400x^2+49+140x+100x^2-92+10x=0

-300x+150x-18=0 |3

-100x+50x-6=0

D=2500-2400=100

x1=-50+10/-200=40/200=20/100=0.2

x2=-50-10/-200=60/200=0.3

 

2)х^2-х+3/4=0 |*4

4x^2-4x+3=0

D=16-48=-32  корней нет

 

3)-0,04+х^2=0

x^2=0.04

x1=0.2

x2=-0.2

 

5)х^2+3,2х-9=0 |*10

10x^2+32x-90=0

D=1024+3600=4624   68

x1=-32+68/20=1.8

x2=-32-68/20=-5

 

 

4)1/6х^2-х+3/4=0 |*12

2x^2-12x+9=0

D=144-72=72

x1=12+sqrt72/4=12+6sqrt2/4=6(2+sqrt2)/4=6+3sqrt2/4

x2=12-sqrt72/4=6-3sqrt2/4

 

 

sqrt - квадратный корень