How do you solve the equation #x^2+1.4x=1.2# by completing the square?

Question

1782 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-05-19T14:30:37

#x=0.6# or #x=-2#

Divide the coefficient of the #x# term by #2# and square it.

#1.4/2=0.7#

#(0.7)^2=0.49#

Now add it to both sides of the equation

#x^2+1.4x+0.49=1.2+0.49#

This becomes

#(x^2+0.7)^2=1.69#

Take the square root of both sides

#sqrt((x+0.7)^2)=+-sqrt(1.69)#

#x+0.7=+-1.3#

#x=+-1.3-0.7#

#x=1.3-0.7=0.6#

#x=-1.3-0.7=-2#