Question

-4√x+9=20 I got 16 both time i tried but it doesn't work when I check my work so is it no solution?

Answer 1

you cannot solve this
the right hand side is positive, whereas the left had side is less than or equal to zero

Answer 2

Not if we disregard the branch cut in the square root graph and actually consider the negative square root. Then x = 16 would be a possible solution. But with the current rules of math, there is no solution to this problem...