What is the exponent on 10 when you right 5.3 in scientific notation?

Guests at an amusement park must be at least 54 inches tall to be able to ride the roller coaster. which graph represents the set of heights that satisfy this requirement?

If 2(a^2+b^2)=(a+b)^2 then, > a+b=0, > ab=0, > a=b, > 2a=b

Pls the last one and it has to be like number 6