1) x^2=64 is the same as x=the root of 64 which gives us: (+-)8
2) here you must us pq-formel as:
5m^2-5m=60
5m^2-5m-60=0
(m^2-5m-60)/5=0
m^2-m-12=0
m=0,5(+-) the root of 0,25+12
m=0,5(+-)3,5
m1=0,5+3,5
m2=0,5-3,5
15) x^2=7x
x^2-7x=0 here there is two x, so:
x(x-7)=0
x1=0
x2=7
Here you can only use PQ formula in all the others, just as I did in the question number 2