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A= bc(a+d)(b-c) +ac(b+d)(c-a) + ab(c+d)(a-b)
A= bc(ab+ bd -ac -dc ) + ac(bc+cd -ab-ad )+ab(ac+ad-bc-bd)
A=(ab²c + b²cd -abc² -bdc² ) + (abc² + adc² -a²bc -a²cd ) + (a²bc + a²bd - ab²c -ab²d)
A= (ab²c + cb²d -ab²c-ab²d) + (c²ab -abc² -bdc² +adc² ) + ( a²bd +a²bc -a²bc -a²cd)
A= a²(bd-cd) + b²(cd-ad) + c²(ad-bd)
A=a²d(b-c) + b²d(c-a) + c²d(a-b)
A=d(a²b-a²c + b²c-b²a +c²a-c²b)
A=d[b(a²-c²) + c(b²-a²) + a(c² - b²)]
bc(a+d)(b-c)-ac(b+d)(a-c)+ab(c+d)(a-b)
=bc(ab+bd-ac-cd)-ac(ab+ad-bc-cd)+ab(ac+ad-bc-bd)
=ab2c+cb2d-abc2-bc2d-a2bc-a2cd+abc2+ac2d+a2bc+a2bd-ab2c-ab2d
=b2cd-bc2d-a2cd+ac2d+a2bd-ab2d
=bcd(b-c)+a2d(b-c)-ad(b2-c2)
=bcd(b-c)+a2d(b-c)-ad(b-c)(b+c)
=(b-c)[bcd+a2d-ad(b+c)]
=(b-c)(bcd+a2d-abd-acd)
=(b-c)[ad(a-c)-bd(a-c)]
=(b-c)(a-c)(ad-bd)
=(b-c)(a-c)(a-b)d
Ta có:
\(A=bc\left(a+d\right)\left(b-c\right)-ac\left(b+d\right)\left(a-c\right)+ab\left(c+d\right)\left(a-b\right)\)
\(=bc\left(a+d\right)\left[\left(b-a\right)+\left(a-c\right)\right]-ac\left(a-c\right)\left(b+d\right)+ab\left(c+d\right)\)\(\left(a-b\right)\)
\(=bc\left(a+d\right)\left(a-b\right)+bc\left(a+d\right)\left(a-c\right)-ac\left(b+d\right)\left(a-c\right)\)\(+ab\left(c+d\right)\left(a-b\right)\)
\(=b\left(a-b\right)\left[a\left(c+d\right)-c\left(a+d\right)\right]+c\left(a-c\right)\left[b\left(a+d\right)-a\left(b+d\right)\right]\)
\(=b\left(a-b\right).d\left(a-c\right)+c\left(a-c\right).d\left(b-a\right)\)
\(=d\left(a-b\right)\left(a-c\right)\left(b-c\right)\)
a:
\(a^3+a^2c-abc+b^2c+b^3\)
\(=\left(a+b\right)\left(a^2-ab+b^2\right)+c\left(a^2-ab+b^2\right)\)
\(=\left(a^2-ab+b^2\right)\left(a+b+c\right)=0\)(vì a+b=c=0)
câu b bn xem ở link này nha!
Giải toán trên mạng - Giúp tôi giải toán - Hỏi đáp, thảo luận về toán học - Học toán với OnlineMath
\(3,=\left(x-y\right)^3+\left(y-x+x-z\right)^3+\left(z-x\right)^3\\ =\left(x-y\right)^3+\left(y-x\right)^3+3\left(y-x\right)\left(x-z\right)\left(y-x+x-z\right)+\left(x-z\right)^3+\left(z-x\right)^3\\ =\left(x-y\right)^3-\left(x-y\right)^3+3\left(y-x\right)\left(x-z\right)\left(y-z\right)-\left(z-x\right)^3+\left(z-x\right)^3\\ =3\left(y-x\right)\left(x-z\right)\left(y-z\right)\)
\(4,=\left(x^4+3x^3-x^2\right)+\left(3x^3+9x^2-3x\right)-\left(x^2+3x-1\right)\\ =x^2\left(x^2+3x-1\right)+3x\left(x^2+3x-1\right)-\left(x^2+3x-1\right)\\ =\left(x^2+3x-1\right)\left(x^2+3x-1\right)\\ =\left(x^2+3x-1\right)^2\)
bc(a+d) 9b –c) – ac( b +d) (a-c) + ab(c+d) ( a-b)
= bc(a+d) [ (b-a) + (a-c)] – ac(a-c)(b+d) +ab(c+d)(a-b)
= -bc(a+d )(a-b) +bc(a+d)(a-c) –ac(b+d)(a-c) + ab(c+d)(a-b)
= b(a-b)[ a(c+d) –c(a+d)] + c(a-c)[ b(a+d) –a(b+d)]
= b(a-b). d(a-c) + c(a-c) . d(b-a)
= d(a-b)(a-c)(b-c)
=d(a-b)(c-a)(c-b)