Question

помогите срочно !!!!!​

Answer 1

$7-x(x-2)=5-x^{2} ;\\7-x^{2} +2x=5-x^{2} ;\\7-5=-x^{2} +x^{2} -2x;\\2=-2x|:2;\\x=-1;\\-------------\\3x(x-5)=3x^{2} -5x+20;\\3x^{2} -15x=3x^{2} -5x+20;\\-15x=-5x+20;\\-15x+5x=20;\\-10x=20|:(-10);\\x=-2.$