Question

1) 2x(x+2) = 5(x+2)
2) lg25/lg5 =

Answer 1

1)
2x(x+2)=5(x+2)
2x^2+4x=5x+10
2x^2-x-10=0.
a=2; b=-1; c=-10.
D= b^2-4ac = 1+80 = 81 = 9

x1= -b-√d:2a = 1-9:4=-2
x2=-b+√d:2a = 1+9:4 = 5:2 = 2,5