Question

giúp vs ạ:33

Answer 1

a) \(\dfrac{x-1}{5}\)=\(\dfrac{3}{y+4}\)

⇒( x - 1)( y + 4) = 3.5 = (-3)(-5) = 5.3 = (-5)(-3) = 1.15 = (-1)(-15)

x - 1	1	-1	3	-3	5	-5	15	-15
x	2	0	4	-2	6	-4	16	-14
y + 4	15	-15	5	-5	3	-3	1	-1
y	11	-19	1	-9	-1	-7	-3	-5

 

Vậy \(\left\{{}\begin{matrix}x=2\\y=11\end{matrix}\right.\); \(\left\{{}\begin{matrix}x=0\\y=-19\end{matrix}\right.\); \(\left\{{}\begin{matrix}x=4\\y=1\end{matrix}\right.\);.........\(\left\{{}\begin{matrix}x=-14\\y=-5\end{matrix}\right.\)

b) A= 1+\(3^2\)+\(2^2\).\(3^3\)+\(3^2\).\(3^2\)+\(3^2\).\(4^2\)+\(3^2\).\(5^2\)+\(3^2\).\(6^2\)+.....\(3^2\).\(12^2\)

       =\(3^2\).(\(\dfrac{1}{3}^2\)+\(2^2\)+\(3^2\)+\(4^2\)+\(5^2\)+\(6^2\)+......+\(12^2\))

       =9.(\(\dfrac{1}{9}\)+649)=5842

 

 

Answer 2

b) Vì \(2^2+3^2+...+12^2=649\)

\(=>3^2\left(2^2+3^2+...+12^2\right)=3^2\cdot649\)

\(=>6^2+9^2+...+36^2=5841\)

=> A = \(1+9+5841\) = 5851