Решить ! 1) x+2/x-4=5 2) x^2-4x+4=0 3)x^2-8x+15=0 - вопрос №523602412452244032815042616550 от Lenokguryhr 20.03.2021 04:17

Question

Алгебра: Решить ! 1) x+2/x-4=5 2) x^2-4x+4=0 3)x^2-8x+15=0 4)x^2=-6x+16 5)-5x+x=0 6)4/5x^2-45=0

Lenokguryhr · Answer

1) x + 2 / X - 4 = 5 ; X ≠ 4
x + 2 = 5 * ( x - 4 )
x + 2 = 5x - 20
4x = 22
x = 5,5

2) X² - 4x + 4 = 0
( X - 2 )² = 0
x = 2

3) X² - 8x + 15 = 0
D = 64 - 60 = 4 ; √ D = 2
X1 = ( 8 + 2 ) : 2 = 5
X2 = ( 8 - 2 ) : 2 = 3

4) X² = - 6x + 16
X² + 6x - 16 = 0
D = 36 + 64 = 100 ; √ D = 10
X1 = ( - 6 + 10 ) : 2 = 2
X2 = ( - 6 - 10 ) : 2 = - 8

5) - 5X + X = 0
- 4X = 0
X = 0

6) 4/5X^2 - 45 = 0
0,8X^2 - 45 = 0
0,8 * ( X^2 - 56,25 ) = 0
X^2 = 56,25
X1 = 7,5
X2 = - 7,5