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Question Number 37324 by behi83417@gmail.com last updated on 11/Jun/18

Commented by math khazana by abdo last updated on 12/Jun/18

b) ((√(1+x))/(1+(√x)))=x ⇒ (√(1+x)) =x(1+(√x)) with x≥0if x real  1+x =x^2 (1+2(√x) +x) ⇒1+x=x^(3 ) +x^2  +2x^2 (√x)  (1+x−(x^3 +x))^2 =4x^5  ⇒  (1+x)^2 −2(1+x)(x^3  +x) +(x^(3 ) +x)^2  −4x^5 =0⇒  x^2  +2x+1 −2(x^3  +x +x^4  +x^2 ) +x^6  +2x^4  +x^2   −4x^5  =0 ⇒  x^6  −4x^5  +2x^4  +2x^2  +2x+1−2x^3  −2x −2x^4  −2x^2 =0  ⇒ x^6  −4x^5  −2x^3  +2x+1 =0   the roots of tbepolynom  p(x)=x^6  −4x^5  −2x^3  +2x +1 are  x_1 ∼4,1105 (real)  x_2 ∼0,8572(real)  x_3  ∼i (complex)  x_4 ∼−i(complex)  x_5  ∼−0,4839 +0,2229i (complex)  x_6  ∼−0,4839 −0,2229i(complex) .

b)1+x1+x=x1+x=x(1+x)withx0ifxreal1+x=x2(1+2x+x)1+x=x3+x2+2x2x(1+x(x3+x))2=4x5(1+x)22(1+x)(x3+x)+(x3+x)24x5=0x2+2x+12(x3+x+x4+x2)+x6+2x4+x24x5=0x64x5+2x4+2x2+2x+12x32x2x42x2=0x64x52x3+2x+1=0therootsoftbepolynomp(x)=x64x52x3+2x+1arex14,1105(real)x20,8572(real)x3i(complex)x4i(complex)x50,4839+0,2229i(complex)x60,48390,2229i(complex).

Commented by math khazana by abdo last updated on 12/Jun/18

we can also divide p(x) by x^2  +1 and we get  a polynom with degre 4 in wich we find the roots...

wecanalsodividep(x)byx2+1andwegetapolynomwithdegre4inwichwefindtheroots...

Commented by behi83417@gmail.com last updated on 12/Jun/18

thank you very much.

thankyouverymuch.

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