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Ta có : -78 x 31 - 78 x 24 - 78 x 17 + 22 x 72
= 78 x (-31 - 24 - 17) + 22 x 72
= -78 x 72 + 22 x 72
= 72 x (-78 + 22)
= 72 x -56
= -4032
Ta có :
\(a\left(a-b\right)-b\left(a-b\right)\)
\(=a^2-ab-ab+b^2\)
\(=a^2-2ab+b^2\)
\(a.\left(a-b\right)-b\left(a-b\right)\)
\(=\left(a-b\right)\left(a-b\right)\)
\(=\left(a-b\right)^2\)
\(\dfrac{2}{3}-4\left(\dfrac{1}{2}+\dfrac{3}{4}\right)\\ =\dfrac{2}{3}-4.\dfrac{2+3}{4}\\ =\dfrac{2}{3}-4.\dfrac{5}{4}\\ =\dfrac{2}{3}-5\\ =\dfrac{2-15}{3}\\ =\dfrac{-13}{3}\)
`a)2/3-4(1/2+3/4)`
`=2/3-4*1/2-4*3/4`
`=2/3-2-3`
`=2/3-5`
`=2/3-15/3`
`=-13/3`
`(3x^3 -2x^2 +3x-2):(x^2+1)`
`=(3x^3 +3x)-(2x^2-2):(x^2+1)`
`=(3x^3 +3x)-(2x^2+2) :(x^2+1)`
`=3x(x^2+1)-2(x^2+1):(x^2+1)`
`=(x^2+1)(3x-2):(x^2+1)`
`=3x-2`
`@ Ariko`
\(34.5^2-4^3.3^2-37.2+50\\ =34.25-64.9-37.2\\ =850-576-74\\ =274-74\\ =200\\ 100-\left\{20.\left[3^2.10-3.\left(35-8\right)\right]\right\}\\ =100-\left[20.\left(9.10-3.27\right)\right]\\ =100-\left[20.\left(90-81\right)\right]\\ =100-\left(20.9\right)\\ =100-180\\ =-80\)
b) 34.5² - 4³.3² - 37.2 + 50
= 34.25 - 64.9 - 74 + 50
= 850 - 576 - 74 + 50
= (850 + 50) - (576 + 74)
= 900 - 650
= 250
d) 100 - {20.[3².10 - 3.(35 - 8)]}
= 100 - [20.(9.10 - 3.27)]
= 100 - [20.(90 - 81)]
= 100 - 20.9
= 100 - 180
= -80
\(30:\left\{12.5^2-2.\left[567-\left(2.7^2+8^2.5\right)\right]\right\}\\ =30:\left\{12.25-2.\left[567-\left(2.49+64.5\right)\right]\right\}\\ =30:\left\{12.25-2.\left[567-\left(98+320\right)\right]\right\}\\ =30:\left[12.25-2.\left(567-418\right)\right]\\ =30:\left(12.25-2.149\right)\\ =30:\left(300-298\right)\\ =30:2\\ =15\)
\(3^2\cdot5^2-\left\{4^3\cdot25-3\cdot\left[3\left(17+3\right)^3-7\cdot10^2\right]\right\}\\ =9\cdot25-\left\{64\cdot25-3\cdot\left[3\cdot20^3-700\right]\right\}\\ =225-\left\{1600-3\left[24000-700\right]\right\}\\ =225-\left\{1600-3\cdot23300\right\}\\ =225--68300=68525\)
\(A=\dfrac{16^4.81^3}{9^5.9^4}\)
\(=\dfrac{\left(2^4\right)^4.\left(3^4\right)^3}{9^9}\)
\(=\dfrac{2^{16}.3^{12}}{\left(3^2\right)^9}\)
\(=\dfrac{2^{16}.3^{12}}{3^{18}}\)
\(=\dfrac{2^{16}}{3^6}\)