Question

If x*x-2x-35=0 then x=?

Answer 1

x^2 +5x -7x -35= 0

x( x+5)-7(x+5) = 0

( x-7)(x+5)=0

x= 7,-5

Answer 2

x*x -2x-35=0

D=b^2-4AC

D=(-2)^2-4×1×(-35)

D= 4 +140

D=144

x=-b +√D/2A

x=2 +12/2×1

x=14/2

x=7