求y=x*3-6x*2 12x 4的单调区间.凹凸区间.极值和拐点
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![求y=x*3-6x*2 12x 4的单调区间.凹凸区间.极值和拐点](/uploads/image/f/5734354-58-4.jpg?t=%E6%B1%82y%3Dx%2A3-6x%2A2+12x+4%E7%9A%84%E5%8D%95%E8%B0%83%E5%8C%BA%E9%97%B4.%E5%87%B9%E5%87%B8%E5%8C%BA%E9%97%B4.%E6%9E%81%E5%80%BC%E5%92%8C%E6%8B%90%E7%82%B9)
1.Y=x^(-1.6)2.Y=根号下X3..Y=X^(-16/5)4.Y=X^(-6/7)
换元法,用t=x方换掉,然后配方.t的范围是大于零.y的值域就出来了
x²+1=-x两边平方x⁴+2x²+1=x²x⁴+1=-x²两边平方x^8+2x⁴+1=x⁴x^8+1=-x
x^2-3x+1=0x^2+1=3x同时除以xx+1/x=3所以x^2+1/x^2=(x+1/x)^2-2=3^2-2=7x^2/(x^4+x^2+1)=1/(x^2+1+1/x^2)=1/8
第一问设yˆ5=k3xˆ4因为x=1时,y=2所以2ˆ5=k3*1ˆ464=12kk=16/3所以函数的表达式为yˆ5=(16/3)3xˆ4
原式=(x4-xy3)+(y4-x3y)+(3xy2-3x2y)=x(x3-y3)+y(y3-x3)+3xy(y-x)=(x3-y3)(x-y)-3xy(x-y)=(x-y)(x3-y3-3xy)=(
∵x+y=6,xy=4,∴(1)x2+y2=(x+y)2-2xy,=62-2×4,=28;(2)(x-y)2=x2+y2-2xy,=28-2×4,=20;(3)x4+y4=(x2+y2)2-2x2y2
(1)∵y=x4-5x2,∴y′=4x3+10x-3;(2)∵y=xtanx=xsinxcosx,∴y′=(xsinx)′cosx−(cosx)′xsinxcos2x=sinxcosx+xcos2x;
用点斜式,首先求斜率K,在任意一点斜率K(x)=y‘=4x3-4x当x=2,k=24,所以直线方程就是y-11=24(x-2).
→f`(x)=3x³-4x→f`(2)=3*8-4*2=16=k→切线方程:y-11=16(x-2)(2):令f`(x)=0,→x=0,x=±2√3/3→xε(-∞,-2√3/3),f`(x
∵x+y=a∴x2+y2+2xy=a2又∵x2+y2=b2∴2xy=a2-b2x4+y4=(x2+y2)2-2x2y2=(x2+y2)2-(2xy)22=b4−(a2−b2)22=-12a4+a2b2
x²+1=-3x两边平方x^4+2x²+1=9x²x^4+1=7x²两边平方x^8+2x^4+1=49x^4x^8+1=47x^4两边除以x^4x^4+1/x^
x²+3x+1=0等式两边同除以xx+3+1/x=0x+1/x=-3x²+1/x²=(x+1/x)²-2=(-3)²-2=9-2=7x⁴+
x^2-3x+1=0x^2+1=3xx+1/x=3(x+1/x)^2=9x^2+1/x^2+2=9x^2+1/x^2=7(x^2+1/x^2)^2=49x^4+1/x^4+2=49x^4+1/x^4=
6X^2-7xy-3y^2-x+7y-2=6x^2-(7y+1)x-(3y^2-7y+2)=6x^2-(7y+1)x-(y-2)(3y-1)=[2x-(3y-1)][3x+(y-2)]=(2x-3y+
由x2+2x-1=0.得(X-1)²=0.所以X=1,那么2x4+1/x4+2x3+2x2+3x-6=2+1+2+2+3-6=4
x平方-3x+1=0二边同除以xx-3+1/x=0x+1/x=3x^2+1/x^2=(x+1/x)^2-2=3^2-2=7x^4+1/x^4=(x^2+1/x^2)^2-2=7^2-2=47
(x^4-y^4)÷(x^2+y^2)/(x+y)=(x^2-y^2)(x^2+y^2)÷(x^2+y^2)/(x+y)=(x^2-y^2)(x^2+y^2)*(x+y)/(x^2+y^2)=(x^2