把下列各多項式分解因式(x-4x)²;+8(x-4x)+16

把下列各多項式分解因式(x-4x)²;+8(x-4x)+16


(x-4x)²;+8(x-4x)+16
=(x-4x+4)²;
=(-3x+4)²;
=(3x-4)²;



x^2-2(m-1)x+m^2能寫成一個一次二項式的完全平方,則符合條件的m的值是


x^2-2(m-1)x+m^2
= x^2-2(m-1)x+(m-1)^2+2m-1
=(x-m+1)^2+2m-1
此式符合一次二項式完全平方那麼,
1、1-m≠0即m≠1
2、2m-1=0即m=1/2
綜上得m=1/2



求不定積分:1、∫dx/x^4(2x^2-1)下麵都是分母2、∫x^4/(x+1)^100 dx


第一題:
原式=-∫〔1/x^2(2x^2-1)〕d(1/x).
令1/x=u,則x=1/u.
∴原式=-∫{1/(1/u)^2〔2(1/u)^2-1〕}du
=-∫〔u^4/(2-u^2)〕du
=∫〔(u^4-4+4)/(u^2-2)〕du
=∫〔(u^2+2)(u^2-2)/(u^2-2)〕du+4∫〔1/(u^2-2)〕du
=∫(u^2+2)du+4∫〔1/(u+√2)(u-√2)〕du
=∫u^2du+2∫du+√2∫〔(u+√2-u+√2)/(u+√2)(u-√2)〕du
=(1/3)u^3+2u+√2∫〔1/(u-√2)〕du-√2∫〔1/(u+√2)〕du
=(1/3)(1/x)^3+2/x+√2ln|u-√2|-√2ln|u+√2|+C
=(1/3)/x^3+2/x+√2ln|1/x-√2|-√2ln|1/x+√2|+C
=(1/3)/x^3+2/x+√2ln|1-√2x|-√2ln|1+√2x|+C
第二題:
令x+1=u,得:x=u-1,dx=du.
∴原式=∫〔(u-1)^4/u^100〕du
=∫〔(u^2-2u+1)^2/u^100〕du
=∫〔(u^4+4u^2+1-4u^3-4u+2u^2)/u^100〕du
=∫(1/u^96)du+6∫(1/u^98)du+∫(1/u^100)du-4∫(1/u^97)du-4∫(1/u^99)du
=-(1/95)/u^95-(6/97)/u^97-(1/99)/u^99+(4/96)/u^96+(4/98)/u^98+C
=-1/〔95(x+1)^95〕+1/〔24(x+1)^96〕-6/〔97(x+1)^97〕
+2/〔49(x+1)^98〕-1/〔99(x+1)^99〕+C