a) x^2-x-x^2+10x-25=2
9x-25=2
9x=27
x=27:9
x=3
b) 32-16x+16x^2-40x+25=0
16x^2-56x+57=0
delta=b^2-4ac=3136-3648=512
x1= (-b+√delta)/2a=(56+16√2)/32=8(7+2√2)/32=(7+2√2)/4
x2=(-b-√delta)/2a=(56-15√2)/32=8(7-2√2)/32=(7-2√2)/4
c) x^2-10x+25-x^2=3
-10x+25=3
-10x= -22
x=11/5
