cho x = 11...15 ; y = 11...19 . C/m rằng xy + 4 là số chính phương.
n. c/s n . c/s
a) -2x - (-17)= 9 b) 11 + (15 – x) = 1
c) 53 – 7x = 57 : 55 |
b) 11 + (15 – x) = 1
d) 29 +9.x2 = 110
e) (2x-4).(3-x) = 0
g) 2x + 1 chia hết cho x -2
b: =>15-x=-10
hay x=25
a: =>-2x+17=9
=>-2x=-8
hay x=4
d: \(\Leftrightarrow9x^2=81\)
hay \(x\in\left\{3;-3\right\}\)
e: \(\Leftrightarrow\left[{}\begin{matrix}2x-4=0\\3-x=0\end{matrix}\right.\Leftrightarrow x\in\left\{2;3\right\}\)
12/15 x 26/11 - 12/15 x 9/11 - 12/15 x 6/11 tính nhanh mình tick
\(=\dfrac{12}{15}\times\left(\dfrac{26}{11}-\dfrac{9}{11}-\dfrac{6}{11}\right)=\dfrac{12}{15}\times\dfrac{11}{11}=\dfrac{12}{15}=\dfrac{4}{5}\)
= 12/15 x (26/11 - 9/11 - 6/11)
= 12/15 x 11/11
= 12/15
15/28 x 4/11 + 15/28 x 2/11 + 15/28 x 5/11 = ? Làm ơn giúp mình với
cho a = 2/11 x 15 + 2/15 x 19 + 2/19 x 23 +....+ 2/51 x 55 tính tích a
a:2/11-2/15+2/15-2/19+2/19-2/23.....+2/51-2/55
a : 2/11-2/55
a:8/55
Đúng thì k hộ mik nha
a=2/4(4/11x15+4/15x19+4/19x23+..........+4/51x55
a=2/4(1/11-1/15+1/15-1/19+1/19-1/23+........+1/51-1/55)
a=2/4(1/11-1/55)
a=2/4x4/55
a=2/55
\(A=\frac{2}{11.15}+\frac{2}{15.19}+...+\frac{2}{51.55}\)
\(A=\frac{1}{2}.\left(\frac{4}{11.15}+\frac{4}{15.19}+...+\frac{4}{51.55}\right)\)
\(A=\frac{1}{2}.\left(\frac{1}{11}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}+...+\frac{1}{51}-\frac{1}{55}\right)\)
\(A=\frac{1}{2}.\left(\frac{1}{11}-\frac{1}{55}\right)\)
\(A=\frac{1}{2}.\frac{4}{55}\)
\(A=\frac{2}{55}\)
Cho P = 5/2 x 1 + 4/1 x 11 + 3/11x2 + 1/2 x 15 + 13/15 x 4 + 15/4 x 43 + 13/43 x 18
cho cac so tu nhien x,y. biet 3.x+2.y+11 chia het cho 15. Hoi 18.x+2.y+26 co chia het cho 15 khong? Vi sao.
3x + 2y + 11 \(⋮\)15
<=> 3x + 2y + 11 + 15(x + 1) \(⋮\)15
<=> 3x + 2y + 11 + 15x + 15 \(⋮\)15
<=> 18x + 2y + 26 \(⋮\)15
vậy ...
CAC BAN GIUP MINH NHA MAI MINH THI ROI
giải cho mik rõ ràng và chi tiết nha , giải hộ mik điiiii nha
Bài 3 : Tính bằng cách thuận tiện :
a) 28.400 : ( 100 x 311 - 310 x 100 ) ; b) \(\dfrac{5}{11}+\dfrac{19}{15}\)+ \(\dfrac{6}{11}+\dfrac{11}{16}\)+ \(\dfrac{6}{15}+\dfrac{5}{16}\)
dấu . là nhân hay là phần ngăn cách ở hàng phần nghìn thế
a) \(28400:\left(100\times311-310\times100\right)\)
\(=28400:\left[\left(311-310\right)\times100\right]\)
\(=28400:100\)
\(=284\)
b) \(\dfrac{5}{11}+\dfrac{19}{15}+\dfrac{6}{11}+\dfrac{11}{16}+\dfrac{6}{15}+\dfrac{5}{16}\)
\(=\left(\dfrac{5}{11}+\dfrac{6}{11}\right)+\left(\dfrac{19}{15}+\dfrac{6}{15}\right)+\left(\dfrac{11}{16}+\dfrac{5}{16}\right)\)
\(=1+\dfrac{5}{3}+1\)
\(=\dfrac{8}{3}+1\)
\(=\dfrac{11}{3}\)
a) 28.400 : ( 100 x 311 - 310 x 100 )
= 28.400 : [ 100 x ( 311 - 310 ]
= 28.400 : 100 x 1
= 0.284 x 1
= 0.284
b) \(\dfrac{5}{11}+\dfrac{19}{15}+\dfrac{6}{11}+\dfrac{11}{16}+\dfrac{6}{15}+\dfrac{5}{16}\)
\(=\left(\dfrac{5}{11}+\dfrac{6}{11}\right)+\left(\dfrac{19}{15}+\dfrac{6}{15}\right)+\left(\dfrac{11}{16}+\dfrac{5}{16}\right)\)
\(=1+\dfrac{5}{3}+1\)
\(=\dfrac{11}{3}\)
Tính bằng cách hợp lý: 11/15 x 1/7 + 11/15 x 2 7 + 11/15 x 4/7 giúp mk mk ag cần gấp
\(\dfrac{11}{15}\times\dfrac{1}{7}+\dfrac{11}{15}\times\dfrac{2}{7}+\dfrac{11}{15}\times\dfrac{4}{7}\)
\(=\dfrac{11}{15}\times\left(\dfrac{1}{7}+\dfrac{2}{7}+\dfrac{4}{7}\right)\)
\(=\dfrac{11}{15}\times1=\dfrac{11}{15}\)