a) 4-5+8x•x=15
4-5+8x^2=15
8x^2=-4+5+15
8x^2=16 |: 8
X^2 = 2
B) x+5=3
x= -5+3
x= -2
c) 4x+3=17
4x= -3+17
4x= 14 | :4
x = 14/4= 7/2
d) x+5= 5
x= -5+5
x= 0
e) 7x+8=-3
7x= -8-3
7x= -11 | :7
x= -11/7
f) -5x• x+5+6x•x+5= 19-18x•x+5
-5^2+6x^2-18x^2= -5-5+19+5
x^2-18x^2= -10+19+5
-17x^2= 14 | : (-17)
x^2 = -14/17
g) x+6+y+3=0
x+y = -3-6
x+y= -9