Question

0.4X²-0.5X=1怎么解?

Answer 1

0.4x²-0.5x=1

4x²-5x=10

4(x²-5/4x)=10

4[x²-5/4x+(5/8)²]-4×(5/8)²=10

4(x-5/8)²=10+25/16

4(x-5/8)²=185/16

(x-5/8)²=185/64

剩下的自己解.