Question

81x^2 - 25 = 0
9x^2 - x = 0
4x^2 + 5x - 6 = 0

Answer 1

1)81x²-25=0
   (9x)²-5²=0
  (9x+5)(9x-5)=0
a)9x+5=0, x=-5/9
b)9x-5=0, x=5/9
2)9x²-x=0
   x(9x-1)=0
a)x=0
b)9x-1=0, x=1/9
3)4x²+5x-6=0, D=25+96=121, √D=√121=11
  x1=(-5+11)/8=6/8=3/4=0,75
  x2=(-5-11)/8=-16/8=-2