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24.(52+1)(54+1).........(516+1)
=(52-1)(52+1)(54+1)........(516+1)
=(54-1)(54+1).........(516+1)
=(58-1)(58+1)(516+1)
=(516-1)(516+1)
=532-1
Tính giá trị biểu thức:
a) x6 -50x5 +50x4 -50x3 +...+ 50 tại x= 49
b) 24. (52 +1).(54 +1).... (516 +1)
A = \(\frac{1}{2}.24\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
A = \(\frac{1}{2}\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
A = \(\frac{1}{2}\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
A = \(\frac{1}{2}\left(5^8-1\right)\left(5^8+1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
A = \(\frac{1}{2}\left(5^{16}-1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
A = \(\frac{1}{2}\left(5^{32}-1\right)\left(5^{32}+1\right)\)
A = \(\frac{1}{2}\left(5^{64}-1\right)\)
\(2A=24\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
\(=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\left(5^{32}+1\right)\)
\(=5^{64}-1\)
=> \(A=\frac{5^{64}-1}{2}\)
Đặt \(A=12.\left(5^2+1\right).\left(5^4+1\right).\left(5^8+1\right).\left(5^{16}+1\right)\)
\(\Rightarrow2A=24.\left(5^2+1\right).\left(5^4+1\right).\left(5^8+1\right).\left(5^{16}+1\right)\)
\(2A=\left(5^2-1\right).\left(5^2+1\right).\left(5^4+1\right).\left(5^8+1\right).\left(5^{16}+1\right)\)
\(2A=\left(5^4-1\right).\left(5^4+1\right).\left(5^8+1\right).\left(5^{16}+1\right)\)
\(2A=\left(5^8-1\right).\left(5^8+1\right).\left(5^{16}+1\right)\)
\(2A=\left(5^{16}-1\right).\left(5^{16}+1\right)\)
\(2A=\left(5^{16}\right)^2-1^2\)
\(2A=5^{32}-1\)
\(\Rightarrow A=\frac{5^{32}-1}{2}.\)
\(A=4x^2-2\left(y+2,5x^2\right)+x^2-4y\)
\(=4x^2-2y-5x^2+x^2-4y=-6y\)
\(B=\left(x+y\right).\left(x^4-x^3y+x^2y^2-xy^3+y^4\right)-\left(x^5+y^5-8\right)\)
\(=x^5-x^4y+x^3y^2-x^2y^3+xy^4+x^4y-x^3y^2+x^2y^3-xy^4+y^5-x^5-y^5+8\)
\(=8\)
Vậy BT B ko phụ thuộc vào biến
câu sau tương tự
\(5x\left(x+1\right)-3\left(x-5\right)+4\left(3x-6\right)=2x^2-7\)
\(\Rightarrow5x^2+5x-3x+15+12x-24=2x^2-7\)
\(\Rightarrow5x^2+14x-9=2x^2-7\Rightarrow5x^2+14x-9-2x^2+7=0\)
\(\Rightarrow3x^2+14x-2=0\)
\(\Rightarrow3\left(x^2+\frac{14}{3}x-\frac{2}{3}\right)=0\Rightarrow x^2+2.x.\frac{7}{3}+\frac{49}{9}-\frac{55}{9}=0\)
\(\Rightarrow\left(x+\frac{7}{3}\right)^2=\frac{55}{9}\Rightarrow x+\frac{7}{3}\in\left\{\sqrt{\frac{55}{9}};-\sqrt{\frac{55}{9}}\right\}\Rightarrow x\in\left\{\sqrt{\frac{55}{9}}-\frac{7}{3};-\sqrt{\frac{55}{9}}-\frac{7}{3}\right\}\)
\(626Q=\left(5^4+1\right)Q=5^{36}+5^{32}-\left(5^2-1\right)\left(5^2+1\right)626\left(5^8+1\right)\left(5^{16}+1\right)=5^{36}+5^{32}-\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)=5^{36}+5^{32}-\left(5^8-1\right)\left(5^8+1\right)\left(5^{16}+1\right)=5^{36}+5^{32}-\left(5^{16}-1\right)\left(5^{16}+1\right)=5^{36}+5^{32}-5^{32}+1=5^{36}+1=\left(5^{12}+1\right)\left(5^{24}-5^{12}+1\right)=\left(5^4+1\right)\left(5^8-5^4+1\right)\left(5^{24}-5^{12}+1\right)\Rightarrow Q=\left(5^8-5^4+1\right)\left(5^{24}-5^{12}+1\right)\)
thanks ạ