How do you solve sqrt(x + 3) = 2x + 1x+3=2x+1?

1 Answer
Aug 10, 2015

x= (-3+-sqrt(41))/8x=3±418

Explanation:

Given sqrt(x+3) = 2x+1x+3=2x+1

Square both sides:
color(white)("XXXX")XXXXx+3 = 4x^2+4x+1x+3=4x2+4x+1

Subtract (x+3)(x+3) from both sides (and reverse sides)
color(white)("XXXX")XXXX4x^2+3x-2=04x2+3x2=0

Using the quadratic formula (see below)
color(white)("XXXX")XXXXx= (-3+-sqrt(41))/8x=3±418

Quadratic formula:
color(white)("XXXX")XXXXfor any quadratic in the general form:
color(white)("XXXX")XXXXcolor(white)("XXXX")XXXXax^2+bx+c=0ax2+bx+c=0
color(white)("XXXX")XXXXthe solutions are given by the formula:
color(white)("XXXX")XXXXcolor(white)("XXXX")XXXXx = (-b+-sqrt(b^2-4ac))/(2a)x=b±b24ac2a