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a)(7.3^5-3^4+3^6):3^4 (7.(3^5=243)-(3^4=81)+(3^6=729)):(3^4=81)=29
b)(16^3-64^2):8^2 ((16^3=4096)-(64^2=4096)):(8^2=64)=0
c)(3x^2y^2+6y^2):3y lấy 3x^2y^2:3y=x^2y rồi lấy 6y^2:3y=2y cộng 2 kết quả lạ
a)(7.243-81+729):81=29
b)(4096-4096):64=0
c)(9x^2.3x^2y+36y^2):3y=3x^2y+12y
a: =2x^5-15x^3-x^2-2x^5-x^3=-16x^3-x^2
b: =x^3+3x^2-2x-3x^2-9x+6
=x^3-11x+6
c: \(=\dfrac{4x^3+2x^2-6x^2-3x-2x-1+5}{2x+1}\)
\(=2x^2-3x-1+\dfrac{5}{2x+1}\)
a) \(6x^3\left(\dfrac{1}{3}x^2-\dfrac{5}{2}-\dfrac{1}{6}\right)-2x^5-x^3\)
\(=6x^3\left(\dfrac{1}{3}x^2-\dfrac{16}{6}\right)-2x^5-x^3\)
\(=2x^5-16x^3-2x^5-x^3\)
\(=-17x^3\)
b) \(\left(x+3\right)\left(x^2+3x-2\right)\)
\(=x^3+3x^2-2x+3x^2+9x-6\)
\(=x^3+6x^2+7x-6\)
c) \(\left(4x^3-4x^2-5x+4\right):\left(2x+1\right)\)
\(=2x^2+4x^3-2x-4x^2-\dfrac{5}{2}-5x+\dfrac{2}{x}+4\)
\(=4x^3-2x^2-7x+\dfrac{2}{x}+\dfrac{3}{2}\)
\(a,\frac{x}{2\left(x-3\right)}+\frac{x}{2\left(x+1\right)}=\frac{2x}{\left(x+1\right)\left(x-3\right)}\)
\(\frac{x\left(x+1\right)}{2\left(x-3\right)\left(x+1\right)}+\frac{x\left(x-3\right)}{2\left(x+1\right)\left(x-3\right)}=\frac{4x}{2\left(x+1\right)\left(x-3\right)}\)
\(x\left(x+1\right)+x\left(x-3\right)=4x\)
\(x^2+x+x^2-3x=4x\)
\(2x^2-2x=4x\)
\(2x^2-2x-4x=0\)
\(2x\left(x-3\right)=0\)
\(2x=0\Leftrightarrow x=0\)
hoặc
\(x-3=0\Leftrightarrow x=3\)
b) \(ĐKXĐ:x\ne\pm4\)
\(5+\frac{96}{x^2-16}=\frac{2x-1}{x+4}-\frac{3x-1}{4-x}\)
\(\Leftrightarrow5+\frac{96}{x^2-16}=\frac{2x-1}{x+4}+\frac{3x-1}{x-4}\)
\(\Leftrightarrow\frac{5\left(x^2-16\right)}{x^2-16}+\frac{96}{x^2-16}=\frac{\left(2x-1\right)\left(x-4\right)}{x^2-16}+\frac{\left(3x-1\right)\left(x+4\right)}{x^2-16}\)
\(\Rightarrow5\left(x^2-16\right)+96=\left(2x-1\right)\left(x-4\right)+\left(3x-1\right)\left(x+4\right)\)
\(\Leftrightarrow5x^2-80+96=2x^2-9x+4+3x^2+11x-4\)
\(\Leftrightarrow5x^2-2x^2-3x^2+9x-11x=4-4+80-96\)
\(\Leftrightarrow-2x=-16\)\(\Leftrightarrow x=8\)( thoả mãn ĐKXĐ )
Vậy tập nghiệm của phương trình là: \(S=\left\{8\right\}\)
Bài 44: (SBT/12):
a. (7.35 - 34 + 36) : 34
= (7.35 : 34) + (-34 : 34) + (36 : 34)
= 7 . 3 - 1 + 32
= 21 - 1 + 9
= 29
b. (163 - 642) : 83
= [(2.8)3 - (82)2 ] : 83
= (23 . 83 - 84) : 83
= ( 23 . 83 : 83) + (-84 : 83)
= 23 - 8
= 8 - 8
= 0
a) \(\left(7.3^5-3^4+3^6\right):3^4\)
\(=7.3^5:3^4-3^4:3^4+3^6:3^4\)
\(=7.3^{5-4}-3^{4-4}+3^{6-4}\)
\(=7.3^1-3^0+3^2\)
\(=7.3-1+9\)
\(=21-1+9\)
\(=20+9\)
\(=29\)
b) \(\left(16^3-64^2\right):8^3\)
\(=\left[\left(2^4\right)^3-\left(2^6\right)^2\right]:\left(2^3\right)^3\)
\(=\left(2^{4.3}-2^{6.3}\right):2^{3.3}\)
\(=\left(2^{12}-2^{12}\right):2^9\)
\(=2^{12-9}-2^{12-9}\)
\(=2^3-2^3\)
\(=8-8\)
\(=0\)