algebra
posted by Felicia on .
square root ( 2x+1) +x=7

√(2x+1) + x = 7
√(2x+1) = 7x
2x+1 = 49  14x + x^2
x^2  16x + 48 = 0
(x12)(x4) = 0
x = 4 or 12
check:
√(2*4+1)+4 = √9 + 4 = 3+4 = 7
√(2*12+1)+12 = √25 + 12 = 5+12 = 17 BOO!
Why? Because this is true only if we take the √: 5+12 = 7, but that's not the original equation. Squaring both sides allowed for using + or  √.