ldcf.net
当前位置:首页 >> 已知α,β是方程x²+2x%5=0的两个实数根,则α&#1... >>

已知α,β是方程x²+2x%5=0的两个实数根,则α&#1...

∵x1,x2是方程x²-3x-5=0的两实根 ∴x1²-3x1-5=0 x1²=3x1+5 2x1²=6x1+10 又,根据韦达定理:x1+x2=3 ∴2x1²+6x2-2015=6x1+10+6x2-2015 = 6(x1+x2)-2005 = 6*3-2005 = - 1987

x²-(a²+a+1)x+a(a²+1)>0 (x-a)(x-(a²+1))>0 xa²+1 (a²+1>a恒成立) A={x|xa²+1} B=[2,4] (y=(1/2)(x-1)²+2) a可取的充要条件是: a>2或a²+1

解: ∫[(x+1)/(x²-2x+5)]dx =∫[(x-1+2)/(x²-2x+5)]dx =∫[(x-1)/(x²-2x+5)]dx+∫[2/(x²-2x+5)]dx =½∫[(2x-2)/(x²-2x+5)]dx +∫1/[(½x-½)²+1]d(½x-½) =½ln(x²-2x+5) +arctan[...

设过点(1,1/2)的圆的切线的切点为(x0,y0)过切点的半径的斜率为yo/x0切线的斜率为(y0-1/2)/(x0-1)∴(y0-1/2)/(x0-1)=-x0/y0整理得x0+1/2y0=x0²+y0&#178...

设f(x)=x³sin²x/(x^4+2x²+1) 可知f(-x)=-x³sin²x/(x^4+2x²+1)=-f(x) 所以被积函数f(x)为奇函数。 又因为积分区间为(5,-5)是对称区间。 根据偶倍奇零的性质,奇函数的对称区间积分为0 所以此题答案为0

解析: //已知x²-x-1=0,求x^5+x⁴+2x-1 x^5+x⁴+2x-1 =x⁴(x+1)+2x-1 =(x+1)³+2x-1 =(x³+3x²+3x+1)+2x-1 =x³+3x²+5x =x(x+1)+3(x+1)+5x =x²+9x+3 =(x+1)+9x+3 =10x+4 =10(1±√5)/2+4 =5(1±√5...

x²+4x-4=0 x²+4x=4 3x²+12x-5 =3(x²+4x)-5 =3·4-5 =12-5 =7

网站首页 | 网站地图
All rights reserved Powered by www.ldcf.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com