a) 2x ( x - 1 ) = 10 - 2x
2x² - 2x = 10 - 2x
2x² - 2x + 2x = 10
2x² = 10
x² = 5
x = √5
b) x ( x + 1 ) = x + 2
x² + x = x + 2
x² + x - x = 2
x² = 2
x = √2
c) x² + x + 3 = 2 + x
x² + x - x = 2 - 3
x² = -1
x = -√1
e) x² + 4x/6 = 2x + 3 / 3
6x² + 4x = 4x + 6
6x² + 4x - 4x = 6
6x² = 6
x² = 1
x = √1
2.
a) x² + 3² = 5²
x² = 25 - 9
x² = 16
x = √16
x = 4
b) 25² - x² = 7²
-x² = 49 - 625
-x² = -576
x = 24
c) 13 + 2x² = x² - 12
2x² - x² = -12 - 13
x² = -25
x = -5