If x2 + 8x-4=x2+8, then 2x-3+?

Answer: The number 0

x^2 + 8x - 4 = x^2 + 8

8x - 4 = 8 ... subtract x^2 from both sides

8x = 12 ... add 4 to both sides

x = 12/8 ... divide both sides by 8

x = 3/2 ... reduce

x = 1.5 ... convert to decimal form

Now plug x = 1.5 into the expression 2x-3 and simplify

2x-3 = 2*1.5-3 = 3-3 = 0 which is the answer