(2^2xIxI-5^2).3^8=3^9
Tim x biet
co bao nhieu so tu nhien co 3 chu so chia het cho3
cho n = 7a5+8b4 biet a-bbang 6va n chia het cho 9tim avab
n = 705 + 10a + 804 + 10b = 1503 + 10a + 10b + 6 = 1503 + 10a + 10b + a - b = 1503 + 11a + 9b chia hết cho 9
1503 và 9b chia hết cho 9 => 11a phải chia hết cho 9 => a = 9 => b = a - 6 = 9 - 6 =3
tim x biet 1- (5/3/8 + x - 7/5/24 ) / 16/2/3 =0
2. Tim x tren y biet
a. x/y + 4/5 = 8/6
b. x/y - 4/5 = 2/3
c. 5/8 * x/y = 5/12
d. x/y : 2/9 = 3/8
tim x biet 5/4*(x-8)=-5/3(14-1/2)
Tìm x biet
A, 2/3 × x - 4/7 = 1/8
B, 2/7 - 8/9 × x = 2/3
C, 4/7 + 5/9 : x = 1/5
a)
\(\dfrac{2}{3}\cdot x-\dfrac{4}{7}=\dfrac{1}{8}\\ \dfrac{2}{3}\cdot x=\dfrac{1}{8}+\dfrac{4}{7}\\ \dfrac{2}{3}\cdot x=\dfrac{39}{56}\\ x=\dfrac{39}{56}:\dfrac{2}{3}\\ x=\dfrac{117}{112}\)
b)
\(\dfrac{2}{7}-\dfrac{8}{9}\cdot x=\dfrac{2}{3}\\ \dfrac{8}{9}\cdot x=\dfrac{2}{7}-\dfrac{2}{3}\\ \dfrac{8}{9}\cdot x=-\dfrac{8}{21}\\ x=-\dfrac{8}{21}:\dfrac{8}{9}\\ x=-\dfrac{3}{7}\)
c)
\(\dfrac{4}{7}+\dfrac{5}{9}:x=\dfrac{1}{5}\\ \dfrac{5}{9}:x=\dfrac{1}{5}-\dfrac{4}{7}\\ \dfrac{5}{9}:x=-\dfrac{13}{35}\\ x=\dfrac{5}{9}:\left(-\dfrac{13}{35}\right)\\ x=-\dfrac{175}{117}\)
A.
\(\dfrac{2}{3}x-\dfrac{4}{7}=\dfrac{1}{8}\)
<=>\(\dfrac{2}{3}x=\dfrac{1}{8}+\dfrac{4}{7}\)
<=>\(\dfrac{2}{3}x=\dfrac{39}{56}\)
<=> \(\dfrac{2}{3}x.\dfrac{3}{2}=\dfrac{39}{56}.\dfrac{3}{2}\)
<=> x= \(\dfrac{117}{112}\)
B.
\(\dfrac{2}{7}-\dfrac{8}{9}x=\dfrac{2}{3}\)
<=> \(\dfrac{-8}{9}x=\dfrac{2}{3}-\dfrac{2}{7}\)
<=> \(\dfrac{-8}{9}x=\dfrac{8}{21}\)
<=> \(\dfrac{-8}{9}x.\dfrac{-9}{8}=\dfrac{8}{21}.\dfrac{-9}{8}\)
<=> x= \(\dfrac{-3}{7}\)
C.
\(\dfrac{4}{7}+\dfrac{5}{9}:x=\dfrac{1}{5}\)
\(\dfrac{5}{9}:x=\dfrac{1}{5}-\dfrac{4}{7}\)
<=>\(\dfrac{5}{9}.\dfrac{1}{x}=\dfrac{-13}{35}\)
<=> \(\dfrac{5}{9x}=\dfrac{-13}{35}\)
<=> 9x= \(\dfrac{5.35}{-13}\)
<=> 9x = \(\dfrac{-175}{13}\)
<=> \(9x.\dfrac{1}{9}=\dfrac{-175}{13}.\dfrac{1}{9}\)
<=> x= \(\dfrac{-175}{117}\)
tim x, y thuoc Z biet 3/x/ phan 2 +5/y/ phan 3=8
Tim x biet
(x+1/5)-4=-2
(2x+3)*(x-7)=0
31/9(x)-5/2=8/3
Ta có : \(\left(2x+3\right)\left(x-7\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}2x+3=0\\x-7=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x=-3\\x=7\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-\frac{3}{2}\\x=7\end{cases}}\)
Tìm x,biết :
\(a,\left(x+\frac{1}{5}\right)-4=-2\)
\(\left(x+\frac{1}{5}\right)=2\)
\(x+\frac{1}{5}=2\)
\(x=\frac{9}{5}\)
b,\(\left(2x+3\right)\left(x-7\right)=0\)
\(\Rightarrow\orbr{\begin{cases}2x+3=0\\x-7=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-\frac{3}{2}\\x=7\end{cases}}\)
\(c,\frac{31}{9}x-\frac{5}{2}=\frac{8}{3}\)
\(\frac{31}{9}x=\frac{8}{3}+\frac{5}{2}\)
\(\frac{31}{9}x=\frac{31}{6}\)
\(x=\frac{3}{2}\)
Vẽ đồ thị hàm số. Nhìn đồ thị, đọc giá trị nhỏ nhất hay lớn nhất ? a. ý= -1/2x2; b. y = -Ix+2I - 1; c. y= -2xIxI
TÌM tọa độ giao điểm của 2 đồ thị sau = phép toán.
1. (D): y= -x+3 và (P): y= -x2
2. (D): y= 2x+3 và (P): y= x2
Tim x biet : ( x + 1 ) + ( x + 2 ) ( x + 3 ) + ( x +4 ) + ( x + 5 ) = 4 + 5 + 6 + 7 + 8
Ta có : ( x+1 ) + ( x + 2 ) + ( x + 3 ) + ( x + 4 ) + ( x + 5 ) = 30
( x + x + x +x +x ) + ( 1 + 2 + 3 + 4 + 5 ) = 30
x * 5 + 15 = 30
x * 5 = 30 - 15
x * 5 = 15
x = 15 : 5
x = 3
Vậy x = 3
Duyệt đi , chúc bạn học giỏi
(x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) = 4 + 5 + 6 + 7 + 8
x + 1 + x + 2 + x + 3 + x + 4 + x + 5 = 30
\(x\)x 5 + 15 = 30
\(x\)x 5 = 30 - 15 = 15
x = 15 : 5 = 3