How do I solve 4x^2 - 6x + 1 = 04x26x+1=0 by completing the square?

1 Answer
Sep 13, 2014

4x^2-6x=-14x26x=1

Factor out a 44

4(x^2-6/4x)=-14(x264x)=1

Simplify fraction

4(x^2-3/2x)=-14(x232x)=1

Take half of x term and square the result

((-3/2)/2)^2=((-3/2)*(1/2))^2=(-3/4)^2=9/16(322)2=((32)(12))2=(34)2=916

Add 4*9/164916 or 9/494 to the right side because we factored out a 44.
Add 9/16916 to the left side.

4(x^2-3/2x+9/16)=-1+9/44(x232x+916)=1+94

4(x-3/4)^2=-1+9/44(x34)2=1+94

4(x-3/4)^2=-4/4+9/44(x34)2=44+94, common denominators -1=-4/41=44

4(x-3/4)^2=5/44(x34)2=54

(x-3/4)^2=(5/4)/4(x34)2=544

(x-3/4)^2=5/16(x34)2=516

sqrt((x-3/4)^2)=+-sqrt(5/16)(x34)2=±516

x-3/4=+-sqrt(5/16)x34=±516

x-3/4=+-sqrt(5)/4x34=±54

x=+-sqrt(5)/4+3/4x=±54+34

x=(+-sqrt(5)+3)/4x=±5+34