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a/ \(5^4.3^4-\left(15^2-1\right)\left(15^2+1\right)\)
\(=15^4-\left(15^4-1^2\right)\)
\(=1\)
\(\left(18^4+1\right)\left(18-1\right)-9^8.2^8\) câu này bn xem lại đề đi nha, chắc bn chép sai đề rồi
b/ \(\frac{77^2+17^2-34.77}{77^2-17^2}\) \(=\frac{77^2-2.17.77+17^2}{\left(77-17\right)\left(77+17\right)}\)
= \(\frac{\left(77-17\right)^2}{\left(77-17\right)\left(77+17\right)}\)
= \(\frac{77-17}{77+17}\)
\(=\frac{60}{94}=\frac{30}{47}\)
\(\frac{135^2+130.135+65^2}{135^2-65^2}=\frac{135^2+2.65.135+65^2}{\left(135-65\right)\left(135+65\right)}\)
\(=\frac{\left(135+65\right)^2}{\left(135-65\right)\left(135+65\right)}\)
\(=\frac{135+65}{135-65}=\frac{200}{70}=\frac{20}{7}\)
chúc bn học tốt
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\(=\dfrac{3}{2\left(x+3\right)}+\dfrac{6-x}{2x\left(x+3\right)}=\dfrac{3x+6-x}{2x\left(x+3\right)}=\dfrac{2x+6}{2x\left(x+6\right)}=\dfrac{2\left(x+3\right)}{2x\left(x+3\right)}=\dfrac{1}{x}\)
\(=\dfrac{3x+6-x}{2x\left(x+3\right)}=\dfrac{2x+6}{2x\left(x+3\right)}=\dfrac{1}{x}\)
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A = 232 + ( 223 + 223-224) + (218 - 217 - 217) + ( 29 + 29 - 210) + 1
= 223 + 1
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2.
\(\left(\dfrac{a}{b^2}+\dfrac{1}{a}-\dfrac{1}{b}\right):\left(\dfrac{b}{a}+\dfrac{a^2}{b^2}\right)\)
\(=\left(\dfrac{a^2}{ab^2}+\dfrac{b^2}{ab^2}-\dfrac{ab}{ab^2}\right):\left(\dfrac{b^3}{ab^2}+\dfrac{a^3}{ab^2}\right)\)
\(=\dfrac{a^2+b^2-ab}{ab^2}:\dfrac{\left(a+b\right)\left(a^2+b^2-ab\right)}{ab^2}\)
\(=\dfrac{a^2+b^2-ab}{ab^2}.\dfrac{ab^2}{\left(a+b\right)\left(a^2+b^2-ab\right)}\)
\(=\dfrac{1}{a+b}\)
1.
\(\left(a-\dfrac{x^2+a^2}{x+a}\right)\left(\dfrac{2a}{x}-\dfrac{4a}{x-a}\right)\)
\(=\dfrac{ax+a^2-x^2-a^2}{x+a}.\dfrac{2ax-2a^2-4ax}{x\left(x-a\right)}\)
\(=\dfrac{ax-x^2}{x+a}.\dfrac{-2a^2-2ax}{x\left(x-a\right)}\)
\(=\dfrac{x\left(a-x\right)}{x+a}.\dfrac{2a\left(x+a\right)}{x\left(x-a\right)}\)
\(=2a\)
lớp 8 mà dễ vậy