Nhanhhhhhhhhhhhhhhhhhhhhhhhhhh

`[` Bạn tham khảo `]`

`(x + 20)^100 + |y + 4| = 0`

Nhận xét:

`(x + 20)^100 >= 0 AA x`

`|y + 4| >= 0 AA y`

`-> (x + 20)^100 + |y + 4| >= 0 AA x,y`

mà: `(x + 20)^100 + |y + 4| = 0`

`-> {(x + 20  = 0),(y + 4 = 0):}`

`-> {(x = -20),(y = -4):}`

Vậy `(x;y) = (-20;-4)`

$\\$

`\color{red}{a,}`

`(4x + 5)/(3x + 15) = 1` `(x \ne -5)`

`<=> 4x + 5 = 3x + 15`

`<=> 4x - 3x = 15 - 5`

`<=> x = 10` `(tm)`

Vậy `x = 10`

$\\$

`(5x + 8)/7 = (4x + 4)/5`

`<=> 5.(5x + 8) = 7.(4x + 4)`

`<=> 25x + 40 = 28x + 28`

`<=> 25x - 28x = 28 - 40`

`<=> -3x = -12`

`<=> x = 4`

Vậy `x = 4`

$\\$

`(2x^2 + 1)/2 = (3x^2 + x - 1)/3`

`<=> 3.(2x^2 + 1) = 2.(3x^2 + x - 1)`

`<=> 6x^2 + 3 = 6x^2 + 2x - 2`

`<=> 6x^2 + 3 - 6x^2 - 2x+  2 = 0`

`<=> -2x + 5 = 0`

`<=> -2x = -5`

`<=> x = 5/2`

Vậy `x = 5/2`

`#Eirlys07`