giả sử a à nghiệm phương trình x²+x-1=0. Tính

A=\(\dfrac{2a-3}{\sqrt{2\left(2a^4-2a+3\right)}+2a^2}\)

giải hpt:

\(\left\{{}\begin{matrix}x+y+z=3\\xy+yz+xz=-1\\x^3+y^3+z^3+6=3\left(x^2+y^2+z^2\right)\end{matrix}\right.\)

giải hpt:

\(\left\{{}\begin{matrix}x^2+y^2+2y=4\\2x+y+xy=4\end{matrix}\right.\)

Cho \(\left\{{}\begin{matrix}x,y>0\\\left(\sqrt{x}+1\right)\left(\sqrt{y}+1\right)\ge4\end{matrix}\right.\). Tìm Min P=\(\dfrac{x^2}{y}+\dfrac{y^2}{x}\).

Cho f(x) = (x⁴+\(\sqrt{2}\)x-7)²⁰¹⁹ . Tính f(a) khi a=\(\left(4+\sqrt{15}\right)\left(\sqrt{5}-\sqrt{3}\right)\).

Cho \(\left\{{}\begin{matrix}a,b>0\\c\ne0\end{matrix}\right.\) và \(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}=0\).

CMR: \(\sqrt{a+b}=\sqrt{b+c}+\sqrt{c+a}\).

Cho x,y \(\in\)N* và \(\left\{{}\begin{matrix}xy+x+7=71\\x^2y+xy^2=880\end{matrix}\right.\).

Tính A=x²+y²

Cho x=\(\dfrac{1}{2}\sqrt{\dfrac{\sqrt{2}-1}{\sqrt{2}+1}}\). Tính A=(4x⁵+4x⁴-x³+1)¹⁹+\(\sqrt{4x^5+4x^4-5x^3+5x}\)+\(\left(\dfrac{1-\sqrt{2}x}{\sqrt{2x^2+2x}}\right)^{2019}\)

giải hpt:

\(\left\{{}\begin{matrix}x^3+3y^2-6y+4=0\\x^2+x^2y^2-2y=0\end{matrix}\right.\)

Use the correct tense or form of the verbs in parentheses.
13 I suggest/_______ elderly people. ( help)

14/ Remember ____________ off the lights before going out. (turn)
15/ Get him __________ the washing machine. ( fix)
16/ What about ____ __________ by bike? ( travel)