\(A\left(x\right)=43x-\left(52x^2+34x^2-8x^4\right)-\left(8x^4+16x^3-42x^2+43x\right)+19\)

\(\Leftrightarrow A\left(x\right)=43x-86x^2+8x^4-16x^3+42x^2-43x+19\)

\(\Leftrightarrow A\left(x\right)=-16x^3-44x^2+19\)

Bậc là: 3

\(5x+5x^2=43x^3\\ \Rightarrow43x^3-5x^2-5x=0\\ \Rightarrow x\left(43x^2-5x-5\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\43x^2-5x-5=0\left(1\right)\end{matrix}\right.\\ \Delta\left(1\right)=25+4.5.43=885\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{5+\sqrt{885}}{86}\\x=\dfrac{5-\sqrt{885}}{86}\end{matrix}\right.\)

Ta có:

.

Chọn: C

Lời giải:

$=65\times 8^2:(4^3\times 2^5)=65\times (2^3)^2:[(2^2)^3\times 2^5]$

$=65\times 2^6:(2^6\times 2^5)=65:2^5=\frac{65}{32}$

\(16.65.8^2:\left(4^3.2^5.16\right)=2^4.65.2^6:\left(2^6.2^5.2^4\right)\)

\(=\dfrac{65}{2^5}=\dfrac{65}{32}\)

\(16\times65\times8^2:\left(4^3\times2^5\times16\right)\)

\(=16\times65\times8^2:\left(4^5\times2^5\right)\)

\(=2^4\times65\times2^6:2^{15}\)

\(=65:2^{10}:2^{15}\)

\(=65:2^5\)

\(=\dfrac{65}{32}\)

Lời giải:

Đặt $A=5+4^2+4^3+....+4^{49}$
$A=1+4+4^2+4^3+...+4^{49}$

$4A=4+4^2+4^3+....+4^{50}$

$\Rightarrow 4A-A=4^{50}-1$

$\Rightarrow 3A=4^{50}-1$

$\Rightarrow 4^{3x-1}-1=4^{50}-1$

$\Rightarrow 3x-1=50$

$\Rightarrow 3x=51$

$\Rightarrow x=17$

Đáp án D