Question

Resolva as equações incompletas do 2 grau
a) x²- 12x = 0
b) ( x = 4)² + 5x. ( x-1) = 16
c) 7x² - x = 0
d) 9x² = 25

Answer 1

x² - 12x = 0
x ( x - 12 ) = 0
x = 0 ***
x - 12 = 0 
x = 12 ****
b
se for 
( x + 4 )² + 5x ( x - 1) = 16
x² + 2.4.x +4² + 5x² - 5x - 16 = 0
x² + 8x + 16 + 5x² - 5x - 16 = 0
6x² + 3x = 0
2x² + x = 0
x ( 2x + 1) = 0
x = 0
2x + 1 = 0
2x = 1
x = 1/2 ***
SE FOR
(X - 4)² + 5X (X - 1) = 16
X² - 8X + 16 + 5X² - 5X - 16 = 0
6X² - 13X  = 0
X ( 6X - 13 ) = 0
X = 0 
6X - 13 = 0
6X = 13
X = 13/6

c
7x² - x = 0
x( 7x - 1) = 0
x = 0 ***
7x - 1 = 0
7x = 1
x = 1/7 ***
d
9x² = 25
x² = 25/9
x= +-V(25/9)
x = +- 5/3 ***