Which value for x makes the sentence true 5+4*=3 squared + x squared

I pretty sure that if you want to make 5+4=3^2+x2, you just have to find a way to make 3^2, 9. So the value of x would have to be 0, because 0*0 is still zero. So the question would become 5+4=9+0, which is true.