Question

5x的平方=4-2x怎么解（一元=次方程）(配方）

Answer 1

5x^2+2x-4=05(x^2+2/5x+1/25)-1/25-4=05(x+1/5)^2-21/5=05(x+1/5)^2=21/5(x+1/5)^2=21/25x+1/5=正负√21/5x=正负√21/5-1/5

Answer 2

5X^2=4-2X(5X)^2+2X=4 想怎样凑成完全平方公式(5X)^2+2X+(1/5)^2=4+(1/5)^2(5x+1/5)^2=4+1/255x+1/5=±√4.045X=√4.04-0.2 5X=-√4.04-0.2X=1.81 X=-2.21

Answer 3

5x�0�5=4-2x5x�0�5+2x=4x�0�5+2x/5=4/5x�0�5+2x/5+(1/5)�0�5=4/5+(1/5)�0�5(X+1/5)�0�5=21/25X+1/5=±（√21）/5X=-1/5±（√21）/5X1=-1/5+（√21）/5X2=-1/5-（√21）/5