如何解一元二次方程4x的平方+70x-246=0

2025-12-15 14:20:03
推荐回答(1个)
回答1:

4x” + 70x - 246 = 0,
2x” + 35x - 123 = 0,
2x” - 6x + 41x - 123 = 0,
2x( x - 3 ) + 41( x - 3 ) = 0,
( x - 3 )( 2x + 41 ) = 0,
或者
2x” + 41x - 6x - 123 = 0,
x( 2x + 41 ) - 3( 2x + 41 ) = 0,
( x - 3 )( 2x + 41 ) = 0,
还可以配方
(4x)” + 70(4x) + 35” - 1225 - 984 = 0,
( 4x + 35 )” - 2209 = 0,
( 4x + 35 )” - ( 47 )” = 0,
( 4x + 35 - 47 )( 4x + 35 + 47 ) = 0,
( 4x - 12 )( 4x + 82 ) = 0,
( x - 3 )( 2x + 41 ) = 0,
解方程得,
x1 = 3,
x2 = -20.5,