a) 2x² + 5 = 7
2x²=7-5
2x²=2
x²=2/2=1
x1=1
x2=-1
x∈{-1,1}
b) 4x² - 2 =0
4x²=2
x²=2/4
x1=√2/2
x2=-√2/2
x∈(-√2/2,√2/2}
c) 19x² + 18 = 17
19x²=17-18
x²=-1/19
x∈Ф
d)2x² = 1- ( -1 ) 2010
2x²=1+2010
2x²=2011
x²=2011/2
x1=√2011/2=√4022/2
x2=-√4022/2
e) 2(x+1)²+4=10
2(x²+2x+1)=10-4
x²+2x+1=6/2
x²+2x+1=3
x²+2x+1-3=0
x²+2x-2=0
Δ=4+8=12
x1=(-2+2√3)/2=-1+√3
x2=-1-√3
f) -7/3x² = - 28/3
-7·3=-28·3x² :-3
7=28x²
x²=28/7
x²=4
x1=2
x2=-2
