1/2(x十2+x+0.4)x=1.

Question

1/2(x十2+x+0.4)x=1.

Answer 1

1/2(x十2+x+0.4)x=1.6
1/2 ( 2x 十2.4 ) x=1.6
( x 十1.2 ) x=1.6
x^2 + 1.2x =1.6
x^2 + 1.2x+0.36 = 1.6+0.36
(x+0.6)^2=1.96
x+0.6=±1.4
x1=2,x2= －0.8