如果(x 3)(x-m)=x的平方 nx 36,则m= n=
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(3-2x)/(x-3)-(2+mx)/(3-x)=-1都乘以x-3得:3-2x+(2+mx)=-x+3解得:x=-2/(m-1)方程无解,∴x=-2/(m-1)是增根x=3即:-2/(m-1)=3解
(x2+mx+8)(x2-3x+n)=x^4+(m-3)x^3+(8+n-3m)x^2+(mn-24)x+8nm-3=08+n-3m=0m=3n=1(-m)^3n=(-3)^3=-27
1X+X2+X3+X4+X5+X6+X7+X8=X(1+X+X2+X3)+X5(1+X+X2+X3)=0+0=02a2+b2+4a-6b+13=(a2+4a+4)+(b2-6b+9)=(a+2)2+(
∵x2+3x-3=0,∴x2+3x=3,∴x3+5x2+3x-10,=x3+3x2+2x2+3x-10,=x(x2+3x)+2x2+3x-10,=3x+2x2+3x-10,=2(x2+3x)-10,=
(12+x)x3=46+x36+3x=46+x3x-x=46-362x=10x=5
x的平方+X+1=0方程式不成立
x+x2+x3+x4+x5+x6+x7+x8=(x+x2+x3+x4)+(x5+x6+x7+x8)=(1+x+x2+x3)*x+(1+x+x2+x3)*x5=0
平均数是3x方差是9M再问:为什么呀再答:失误……平均数是3x+2因为x1.x2.x3........xn的平均数是x,所以x1.x2.x3........xn的和是nx3x1+23x2+23x3+2
由x2+x-1=0得x2+x=1,∴x3+2x2-7=x3+x2+x2-7,=x(x2+x)+x2-7,=x+x2-7,=1-7,=-6.故选C.
如果x^2m-1÷x^2=x^m+1即x^(2m-3)=x^m+12m-3=m+1m=4已知a^m=8,a^n=3,a^k=2,a^m-3k+2n=a^m÷(a^k)³×(a^n)²
∵3x3-x=1,∴9x4+12x3-3x2-7x+2001,=3x(3x3-x-1)+4(3x3-x-1)+2005,=2005.故选D.
x^3+2x^2-7=x(1-x)+2x^2-7=x+x^2-7=1-7=-6
x²+x=0x(x+1)=0所以x=0或x=-1当x=0时,x³+2x+2008=0+0+2008=2008当x=-1时x³+2x+2008=1-2+2008=2007
x3-2x-7=x3+x2-x2+2x-7=(x3+x2-x)-(x2+x-1)-8=x(x2+x-1)-(x2+x-1)-8=-8
x(ax3+x2+b)+3x-2c=ax4+x3+(b+3)x-2c=x3+5x+4得:a=0,b+3=5,-2c=4即a=0,b=2,c=-2a+b+c=0
f(x)=x^3-12x+8?!f'(x)=3x^2-12令f'(x)=0x=2或x=-2则f(x)在x∈(-2,2)递减,x∈(-无穷,-2)和(2,无穷)递增f(-3)=17;f(-2)=24;f
x^2-3x+1=0x^2+1=3xx+1/x=3(x+1/x)^2=9x^2+2+1/x^2=9x^2+1/x^2=7x^3+1/x^3=(x+1/x)(x^2-1+1/x^2)=3x(7-1)=1
括号里是加是减啊?
解法1:设x4+mx3+nx-16=(x-1)(x-2)(x2+ax+b),…(1分)则x4+mx3+nx-16=x4+(a-3)x3+(b-3a+2)x2+(2a-3b)x+2b…(2分)比较系数得