一道化简题(吧)For what integer b can the expression x^2+bx+7 be factored explain.
来源:学生作业帮助网 编辑:六六作业网 时间:2024/10/05 14:11:59
一道化简题(吧)For what integer b can the expression x^2+bx+7 be factored explain.
一道化简题(吧)
For what integer b can the expression x^2+bx+7 be factored explain.
一道化简题(吧)For what integer b can the expression x^2+bx+7 be factored explain.
this expression can be transformed as (x+b/2)^2+7-b^2/4.
when b=-2x,this expression has a minimum value of 7-b^2/4
最后结果是1.5吧? 1=(sin^2a+cos^2a)^2=sin^4+2sin^2a×cos^2a+cos^4a 可以明白? (sin^6a+cos^6a-1) sin^4a+2sin^2a×cos^2a+cos^4a-(sin^6a+cos^6a) --------------- = -------------------------------------------- sin^4a+co...
全部展开
最后结果是1.5吧? 1=(sin^2a+cos^2a)^2=sin^4+2sin^2a×cos^2a+cos^4a 可以明白? (sin^6a+cos^6a-1) sin^4a+2sin^2a×cos^2a+cos^4a-(sin^6a+cos^6a) --------------- = -------------------------------------------- sin^4a+cos^4a-1 sin^4a+2sin^2a×cos^2a+cos^4a-(sin^4a+cos^4a) sin^4+2sin^2a×cos^2a+cos^4a-(sin^6a+cos^6a) = --------------------------------------------① 2sin^2a×cos^2a 根据立方和公式: sin^6a+cos^6a=(sin^2a)^3+(cos^2a)^3 =(sin^2a+cos^2a)(sin^4a-sin^2a×cos^2a+cos^4a) =sin^4a-sin^2a×cos^2a+cos^4a② 把①中sin^6a+cos^6a换成②中的结果可以得: sin^4+2sin^2a×cos^2a+cos^4a-(sin^4a-sin^2a×cos^2a+cos^4a) 原式=------------------------------------------------------------- 2sin^2a×cos^2a 3sin^2a×cos^2a = -----------------=1.5 2sin^2a×cos^2a 不知道结果对不对.但是思路是正确的. 输入的时候排版很好.可是一发布上去就乱了.. 你可以看懂不?就有点儿乱.如果认真看一下还是可以看懂的. --------是分数线...真是抱歉~
收起