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a: \(=ab\cdot\dfrac{4}{3}a^2b^4\cdot7abc=\dfrac{28}{3}a^4b^6c\)

b: \(a^3b^3\cdot a^2b^2c=a^5b^5c\)

c: \(=\dfrac{2}{3}a^3b\cdot\dfrac{-1}{2}ab\cdot a^2b=\dfrac{-1}{3}a^6b^3\)

d: \(=-\dfrac{7}{3}a^3c^2\cdot\dfrac{1}{7}ac^2\cdot6abc=-2a^5bc^5\)

e: \(=\dfrac{-3}{2}\cdot\dfrac{1}{4}\cdot ab^2\cdot bca^2\cdot b=\dfrac{-3}{8}a^3b^4c\)

a: \(A=\left(5xy-2xy+4xy\right)+3x-2y-y^2\)

\(=7xy+3x-2y-y^2\)

b: \(B=\left(\dfrac{1}{2}ab^2-\dfrac{7}{8}ab^2-\dfrac{1}{2}ab^2\right)+\left(\dfrac{3}{4}a^2b-\dfrac{3}{8}a^2b\right)\)

\(=\dfrac{-7}{8}ab^2+\dfrac{3}{8}a^2b\)

c: \(C=\left(2a^2b+5a^2b\right)+\left(-8b^2-3b^2\right)+\left(5c^2+4c^2\right)\)

\(=7a^2b-11b^2+9c^2\)

23 tháng 5 2022

\(A=5xy-y^2-2xy+4xy+3x-2y\)

\(A=-y^2+7xy+3x-2y\)

\(B=\dfrac{1}{2}ab^2-\dfrac{7}{8}ab^2+\dfrac{3}{4}a^2b-\dfrac{3}{8}a^2b-\dfrac{1}{2}ab^2\)

\(B=\dfrac{3}{8}a^2b-\dfrac{7}{8}ab^2\)

\(C=2a^2b-8b^2+5a^2b+5c^2-3b^2+4c^2\)

\(C=7a^2b-11b^2+9c^2\)

11 tháng 11 2023

Đặt \(\dfrac{a}{b}=\dfrac{c}{d}=k\)

=>\(a=bk;c=dk\)

1: \(\dfrac{2a+3c}{2b+3d}=\dfrac{2\cdot bk+3\cdot dk}{2b+3d}=\dfrac{k\left(2b+3d\right)}{2b+3d}=k\)

\(\dfrac{2a-3c}{2b-3d}=\dfrac{2bk-3dk}{2b-3d}=\dfrac{k\left(2b-3d\right)}{2b-3d}=k\)

Do đó: \(\dfrac{2a+3c}{2b+3d}=\dfrac{2a-3c}{2b-3d}\)

2: \(\dfrac{4a-3b}{4c-3d}=\dfrac{4\cdot bk-3b}{4\cdot dk-3d}=\dfrac{b\left(4k-3\right)}{d\left(4k-3\right)}=\dfrac{b}{d}\)

\(\dfrac{4a+3b}{4c+3d}=\dfrac{4bk+3b}{4dk+3d}=\dfrac{b\left(4k+3\right)}{d\left(4k+3\right)}=\dfrac{b}{d}\)

Do đó: \(\dfrac{4a-3b}{4c-3d}=\dfrac{4a+3b}{4c+3d}\)

3: \(\dfrac{3a+5b}{3a-5b}=\dfrac{3bk+5b}{3bk-5b}=\dfrac{b\left(3k+5\right)}{b\left(3k-5\right)}=\dfrac{3k+5}{3k-5}\)

\(\dfrac{3c+5d}{3c-5d}=\dfrac{3dk+5d}{3dk-5d}=\dfrac{d\left(3k+5\right)}{d\left(3k-5\right)}=\dfrac{3k+5}{3k-5}\)

Do đó: \(\dfrac{3a+5b}{3a-5b}=\dfrac{3c+5d}{3c-5d}\)

4: \(\dfrac{3a-7b}{b}=\dfrac{3bk-7b}{b}=\dfrac{b\left(3k-7\right)}{b}=3k-7\)

\(\dfrac{3c-7d}{d}=\dfrac{3dk-7d}{d}=\dfrac{d\left(3k-7\right)}{d}=3k-7\)

Do đó: \(\dfrac{3a-7b}{b}=\dfrac{3c-7d}{d}\)

16 tháng 11 2021

làm ơn trả lời hộ mk với ah mai mk phải nộp bài r

gianroi

15 tháng 6 2020

Lm giúp tôi với :((

15 tháng 6 2020

Bài làm

a) 2a²x³ - ax³ - a⁴ - x³a² - ax³ - 2x⁴

= 2a²x³ - ax³ - a⁴ - a²x³ - ax³ - 2x⁴

= ( 2a²x³ - a²x³ ) - ( ax³ + ax³ ) - a⁴ - 2ax⁴

= a²x³ - 2ax³ - a⁴ - 2ax⁴

b) 3xx⁴ + 4xx³ - 5x²x³ - 5x²x²

= 3x⁵ + 4x⁴ - 5x⁵ - 5x⁴

= ( 3x⁵ - 5x⁵ ) + ( 4x⁴ - 5x⁴ )

= -2x⁵ - x⁴

c) 3a - 4b² - 0,8b . 4b² - 2ab . 3b + b . 3b² - 1

= 3a - 4b² - 3,2b³ - 6ab² + 3b³ - 1

= 3a - 4b² - 0,2b³ - 6ab² - 1

d) 5x.2y² - 5x.3xy - x²y + 6xy² 

= 10xy² - 15x²y - x²y + 6xy²

= ( 10xy² + 6xy² ) - ( 15x²y + x²y )

= 16xy² - 16x²y

27 tháng 3 2022

a, \(A=5x^3+6x^3+x^3-x^2+2x^3-4x^2=14x^3-5x^2\)

b, \(B=2a^2-b^2+3a^2-\left(5a^2-11ab+8b^2+2b^2+7a^2-5ab\right)\)

\(=5a^2-b^2-12a^2+16ab-10b^2=-7a^2-11b^2+16ab\)