Question

[Nguyen Tuan Kiet]

So Sánh:

a 7 + \(\sqrt{5}\) với \(\sqrt{48}+2\)

b \(\sqrt{\left(1-\sqrt{50}\right)^2}\) với 6

Tìm x,y biết: 3x² - 3xy - 5x - y = -20

Tính:

3(x - 2) -4(2x + 1) - 5(2x + 3) = 50

\(\left(\frac{69}{167}-\left(2+\left(3+\left(4+5^{-1}\right)^{-1}\right)^{-1}\right)^{-1}\right)^{-1}\)

GIÚP MÌNH VỚI MAI NỘP RÒI!!!!!!!!

Answer 1

[Vũ Minh Tuấn]

Tính:

\(3.\left(x-2\right)-4.\left(2x+1\right)-5.\left(2x+3\right)=50\)

\(\Rightarrow3x-6-\left(8x+4\right)-\left(10x+15\right)=50\)

\(\Rightarrow3x-6-8x-4-10x-15=50\)

\(\Rightarrow-15x-25=50\)

\(\Rightarrow-15x=50+25\)

\(\Rightarrow-15x=75\)

\(\Rightarrow x=75:\left(-15\right)\)

\(\Rightarrow x=-5.\)

Vậy \(x=-5.\)

Chúc bạn học tốt!

Answer 2

[Khánh Linh]

\(3x^2-3xy-y-5x=-20\)

\(\Rightarrow\)\(3x\left(x-y\right)-y-5x=-20\)

\(\Rightarrow\)\(3x\left(x-y\right)+x-y-6x=-20\)

\(\Rightarrow\)\(3x\left(x-y\right)+\left(x-y\right)-6x=-20\)

\(\Rightarrow\)\(\left(x-y\right)\left(3x+1\right)-6x=-20\)

\(\Rightarrow\)\(\left(x-y\right)\left(3x+1\right)-6x-2=-22\)

\(\Rightarrow\)\(\left(x-y\right)\left(3x+1\right)-\left(6x+2\right)=-22\)

\(\Rightarrow\left(x-y\right)\left(3x+1\right)-2\left(3x+1\right)=-22\)

\(\Rightarrow\left(3x+1\right)\left(x-y-2\right)=-22\)

Ta có bảng sau:

\(3x+1\)	\(-1\)	\(1\)	\(-22\)	\(22\)
\(x\)	\(x\notin Z\)	\(0\)	\(x\notin Z\)	\(7\)
\(x-y-2\)		\(-22\)		\(-1\)
\(y\)		\(-20\)		\(6\)

Vậy ta có 2 bộ (x,y) là (0;-20) và (7;6)

Chúc bạn học tốt!