Question

2X的平方+7x-1等于19-x的平方

Answer 1

2X^2+7X-1=19-X^2

3X^2+7X-20=0

X1=(-7+(49+4*3*20)^0.5)/6=(-7+289^0.5)/6

X1=(-7-(49+4*3*20)^0.5)/6=(-7-289^0.5)/6

2X^2+7X-1=(19-X)^2

2X^2+7X-1=19^2-38X+X^2

X^2+45X-362=0

X1=-45/2+((45/2)^2+362)^0.5=-45/2+(3473^0.5)/2=(-45+3473^0.5)/2

X2=-45/2-((45/2)^2+362)^0.5=-45/2-(3473^0.5)/2=(-45-3473^0.5)/2