Question

解方程2x方-3x+2x根号x方-3x+4=21

Answer 1

2x方-3x+2x根号x方-3x+4=21

2x^2-3x+2x√(x^2-3x+4)=21

x^2-3x+4+2x√(x^2-3x+4)+x^2=25

[√(x^2-3x+4)+x]^2=25

√(x^2-3x+4)+x=±5

√(x^2-3x+4)+x=5

√(x^2-3x+4)=5-x

x^2-3x+4=25+x^2-10x

7x=21

x=3

或

√(x^2-3x+4)+x=-5

√(x^2-3x+4)=-5-x

x^2-3x+4=25+x^2+10x

13x=-21

x=-21/13