同步导学与优化训练九年级上册英语的答案

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同步导学与优化训练九年级上册英语的答案,第1张

定义解一元二次方程的一种方法，也指套用公式计算某事务。

另外还有配方法、直接开方法与因式分解法。 ]步骤1.化方程为一般式ax^2+bx+c=0；

2.确定判别式，计算b^2-4ac；

3.若b^2-4ac≥0，代入公式x=[-b±√(b^2-4ac)]/2a；

若b^2-4ac<0，该方程在实数域内无解，在虚数域内解为x=[-b±√(4ac-b^2)]/2a。 ]实例解方程2x^2+4x-2=0。

解：x^2+2x-1=0

A=1 B=2 C=-1

b^2-4ac=2^2-4×1×[－1]=4+4=8

代入公式x=[-b±√(b^2-4ac)]/2a 得x=[-2±√8]/2×1=-1±√2

X1=-1+√2

X2=-1-√2

易懂方法

解方程2x的方+4x-2=0

解：x的方+2x-1=0

此方程中先整理为一般形式

A=1 B=2 C=-1

b的方-4ac=2的方-4×1×[－1]=4+4=8

带入x=2a分之-b加减根号下（b的方-4ac）得x=2x1分之[-2±根号8]=-1±根号2

X1=1加根号2

X2=1减根号2 [编辑本段]注意事项一定不会出现不能用公式法解一元二次方程的情况。（所谓“一元二次方程万能公式”）

但在能直接开方或者因式分解时最好用直接开方法和分解因式法。

只适用于初中阶段。

胡则錾抽异呈作屏阎菜畿牟赠咚锒衍高隰舡分雟

The experience of using IT exists almost

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The experience of using IT exists almost the entire work field. It has become a critical part of employees’ overall work experience. When IT is operating as it should, employee self-confidence swells. Their job satisfaction, too, can surge when well-functioning machines relieve them of dull tasks or repetitive processes. But if there’s one thing that causes widespread employee frustration, it’s an IT transformation project gone wrong, where swollen expectations have been popped and a long list of promised efficiencies have been reversed . This occurs when business leaders implement (执行) IT initiatives with little consideration of how those changes will impact the end user, which is why managers should appreciate just how influential

the IT user experience is to their employees, and make substantial effort in ensuring their IT team eliminates programming errors and application crashes. Adequate and timely IT support should also be available to enable users to cope with technological issues at work. More importantly, IT practitioners need to understand what employees experience mentally when they use IT.

Therefore, businesses need to set up their IT infrastructure (基础设施) so that it is designed to fit in with their employees’ work, rather than adjust their work to fit in with the company’s IT limitations.