$(x + 3)^2 - 4x^2 = 0$
$(x + 3)^2 - (2x)^2 = 0$
(x + 3 − 2x)(x + 3 + 2x) = 0
(3 − x)(3x + 3) = 0
3 − x = 0
x = 3
или
3x + 3 = 0
3x = −3
x = −1
Ответ: −1 и 3

$16x^2 - (x - 5)^2 = 0$
$(4x)^2 - (x - 5)^2 = 0$
(4x − (x − 5))(4x + x − 5) = 0
(4x − x + 5)(5x − 5) = 0
(3x + 5)(5x − 5) = 0
3x + 5 = 0
3x = −5
$x = -\frac{5}{3} = -1\frac{2}{3}$
или
5x − 5 = 0
5x = 5
x = 1
Ответ: $-1\frac{2}{3}$ и 1

$(x - 2)^2 - 9x^2 = 0$
$(x - 2)^2 - (3x)^2 = 0$
(x − 2 − 3x)(x − 2 + 3x) = 0
(−2x − 2)(4x − 2) = 0
−2x − 2 = 0
−2x = 2
x = −1
или
4x − 2 = 0
4x = 2
x = 0,5
Ответ: −1 и 0,5

$25x^2 - (x + 4)^2 = 0$
$(5x^2) - (x + 4)^2 = 0$
(5x − (x + 4))(5x + x + 4) = 0
(5x − x − 4)(6x + 4) = 0
(4x − 4)(6x + 4) = 0
4x − 4 = 0
4x = 4
x = 1
или
6x + 4 = 0
6x = −4
$x = -\frac{4}{6} = -\frac{2}{3}$
Ответ: $-\frac{2}{3}$ и 1