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解方程:0.25x-4分之1=x+0.5 计算:-2³-(1-0...

(1) 两边开方,得2(x - 1) = 3(x - 5)或2(x - 1) = -3(x - 5), 分别得x = 13和x = 17/5 (2) 只好套公式: x = (7 ± √41)/2 (3) (x - 2)(x + 1) = 0 x = 2, x = -1

1. x^2+10x+16=0 x^2+2*5x+25-25=16=0 (x+5)^2=9 x+5=±3 x1=-2 x2=-8 2. x^2-x-3/4=0 x^2-2*1/2x+1/4-1/4-3/4=0 (x-1/2)^2=1 x-1/2=± 1 x1=3/2 x2=-1/2

先用二项式定理把两边展开: 1+5x+10x²+10x³+5(x^4)+(x^5)=1-5x+10x²-10x³+5(x^4)-(x^5) 移项,合并,整理可得: 10x+20x³+2(x^5)=0 x[(x^4)+10x²+5]=0 x[(x²+5)²-20]=0 x[x²+5+2√5][x²+5-2√5]...

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

(1+x²)y dx-(2-y)x dy=0 (1+x²)y dx =(2-y)x dy 【(1+x²)/x】dx =【(2-y)/y】dy (x+1/x)dx=(-1+2/y)dy d(0.5x²+Inx)= d(-y+2Iny) 0.5x²+Inx = -y+2Iny+C 0.5x²+y=In(C y²/x) C y²...

(-b±√(b²-4ac))/2a a=1 b=-4 c=-1 (-b±√(b²-4ac))/2a =(4±√(16+4))/2 =(4±2*√5))/2 =2±√5

ax²+bx+c≥0的解集是{x|负3分之1≤x≤2}, ∴a<0;c/a=-1/3×2=-2/3;-b/a=-1/3+2=5/3 ∴c=-2/3a,b=-5/3a ∵cx²+bx+a>0 ∴-2/3ax²-5/3ax+a>0 ∵a<0 ∴-2/3x²-5/3x+1<0 ∴2x²+5x-3>0 ∴(x+3)(2x-1)>0 ∴x<-3,或x>1/2 ∴D...

圆心是(2,-1) 圆心到直线距离是|2-2-3|/√(1²+2²)=3/√5 即弦心距是3/√5 半径是2 所以弦长=2√[2²-(3/√5)²]=2√55/5

过程如下 如果您认可我的回答,请及时点击右下角的【好评】按钮 (1) 25X²–4=0 (5x+2)(5x-2)=0 x=-2/5或x=2/5 (2) 2(t–1)²+t–1=0 (t-1)(2(t-1)+1)=0 (t-1)(2t-1)=0 t=1或t=1/2 (3) X²+4X=–4 X²+4X+4=0 (x+2)²=...

由题意得:x1+x2=m,x1*x2=2m-1 因为x1^2+x2^2=7 所以(x1+x2)^2-2x1*x2=7 即m^2-2(2m-1)=7 m^2-4m-5=0 (m-5)(m+1)=0 m=5或m=-1 当m=5时,△<0,所以不合题意,应舍去 当m=-1时,△>0,有意义 则m=-1 所以x1+x2=-1,x1*x2=-3 则(x1-x2)^2=x1^2+x2...

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