Tìm \(x:\)
\(3x+3x+1+3x+2=117\)
Tìm x biết 3x+3x+1+3x+2=117
\(3x+3x+1+3x+2=117\)
\(\Rightarrow\left(3x+3x+3x\right)+\left(1+2\right)=117\)
\(\Rightarrow9x+3=117\)
\(\Rightarrow9x=117-3\)
\(\Rightarrow9x=114\)
\(\Rightarrow x=114:9\)
\(\Rightarrow x=\frac{38}{3}\)
Vậy \(x=\frac{38}{3}\)
P/s : Đúng nha
~ Ủng hộ nhé
a) 3x + 3x+1 + 3x+2 =117
b) 3 + 4 (x - 10) = 32 + 6
a)
\(3^x+3^{x+1}+3^{x+2}=117\\ \Leftrightarrow3^x+3.3^x+9.3^x=117\\ 13.3^x=117\\ \Leftrightarrow3^x=9\\ \Leftrightarrow3^x=3^2\\ \Leftrightarrow x=2\)
b)
\(3+4\left(x-10\right)=3^2+6\\ \Leftrightarrow3+4\left(x-10\right)=15\\ \Leftrightarrow4\left(x-10\right)=12\\ \Leftrightarrow x-10=3\\ \Leftrightarrow x=13\)
a) \(3^x+3^{x+1}+3^{x+2}=117\)
\(3^x+3^x.3+3^x.3^2=117\)
\(3^x.\left(1+3+3^2\right)=117\)
\(3^x.13=117\)
\(3^x=9\)
\(x=2\)
b) \(3+4\left(x-10\right)=3^2+6\)
\(3+4x-40=9+6\)
\(4x=15+40-3\)
\(4x=52\)
\(x=13\)
\(3x+3x+1+3x+2=117\)
tìm x
3x+3x+1+3x+2=177
9x+3=117
9x=117-3
9x=114
x=114/9
\(3x+3x+1+3x+2=117\)
\(\Leftrightarrow\left(3x+3x+3x\right)+\left(1+2\right)=117\)
\(\Leftrightarrow9x+3=117\)\(\Rightarrow9x=114\Rightarrow x=\frac{114}{9}\)
\(\text{Vậy x=}\frac{114}{9}\)
3x+3x+1+3x+2=117
=>3x.3 +(1+2) = 117
=>9x +3 = 117
=> 9x = 114
=> x = \(\frac{38}{3}\)
3x + 3x+1 + 3x+2 = 117
\(3^x+3^{x+1}+3^{x+2}=117\)
\(3^x+3^x.3+3^x.3^2=117\)
\(3^x\left(1+3+3^2\right)=117\)
\(3^x.13=117\)
\(3^x=9\)
\(\Rightarrow x=2\)
`3^{x}+3^{x+1}+3^{x+2}=117`
`3^{x}.(1+3+3^{2})=117`
`3^{x}.13=117`
`3^{x}=117:13=9`
`3^{x}=3^{2}`
`x=2`
\(3^x+3^{x+1}+3^{x+2}=117\)
\(3^x\left(1+3+3^2\right)=117\)
\(3^x\times13=117\)
\(3^x=9\)
\(3^x=3^2\)
\(x=2\)
bài 1: Tính giá trị biểu thức
A = x(3x-y)-(3x+1)y tại x = 4/3; y = -1
B = \(3\frac{1}{117}.\frac{1}{119}-\frac{4}{117}.5\frac{118}{119}-\frac{8}{39}\)
Bài 2: Tìm m và n để hai đa thức đồng nhất:
f(x)=(m-1)x^2+3x+1
g(x) = x^2-nx+1
Bài 1:
Thay \(x=\frac{4}{3};y=-1\)vào biểu thức A, ta được:
\(A=\frac{4}{3}\cdot\left[3\cdot\frac{4}{3}-\left(-1\right)\right]-\left(3\cdot\frac{4}{3}+1\right)\left(-1\right)\)
\(A=\frac{20}{3}+5=\frac{35}{3}\)
Vậy khi \(x=\frac{4}{3};y=-1\)thì A=\(\frac{35}{3}\)
\(B=3\frac{1}{117}\cdot\frac{1}{119}-\frac{4}{117}\cdot5\frac{118}{119}-\frac{8}{39}\)
\(B=\frac{352}{117}\cdot\frac{1}{119}-\frac{4}{117}\cdot\frac{713}{119}-\frac{8}{39}=-\frac{412}{1071}\)
tìm x y biết x/5 = x/6 và -3x - 4y = -117
\(\dfrac{x}{5}=\dfrac{y}{6}\Rightarrow\dfrac{-3x}{-15}=\dfrac{4y}{24}\)
Áp dụng t/c của DS bằng nhau, ta có: \(\dfrac{-3x-4y}{-15-24}=\dfrac{-117}{-39}=3\)
\(\dfrac{-3x}{-15}=3\Rightarrow x=15\)
\(\dfrac{4y}{24}=3\Rightarrow y=18\)
cho biểu thức : A=( 3x+1/3x-1 - 3x-1/3x+1): 3x/ 6x-2.
a) Rút gọn A
b) Tìm x để A=1
c) Tìm x để A>0
Tìm min
F=3x^2 +x -2
G= 4x^2+2x-1
H=5x^2-x+1
Tìm max
A= -x^2 -6x+3
B=-x^2+8x-1
C= -x^2-3X+4
D= -2x^2+3x-1
E= -3x^2 – x +2
F= -5x^2 -4x +3
G= -3x^2 – 5x+1
Tìm min:
$F=3x^2+x-2=3(x^2+\frac{x}{3})-2$
$=3[x^2+\frac{x}{3}+(\frac{1}{6})^2]-\frac{25}{12}$
$=3(x+\frac{1}{6})^2-\frac{25}{12}\geq \frac{-25}{12}$
Vậy $F_{\min}=\frac{-25}{12}$. Giá trị này đạt tại $x+\frac{1}{6}=0$
$\Leftrightarrow x=\frac{-1}{6}$
Tìm min
$G=4x^2+2x-1=(2x)^2+2.2x.\frac{1}{2}+(\frac{1}{2})^2-\frac{5}{4}$
$=(2x+\frac{1}{2})^2-\frac{5}{4}\geq 0-\frac{5}{4}=\frac{-5}{4}$ (do $(2x+\frac{1}{2})^2\geq 0$ với mọi $x$)
Vậy $G_{\min}=\frac{-5}{4}$. Giá trị này đạt tại $2x+\frac{1}{2}=0$
$\Leftrightarrow x=\frac{-1}{4}$
Tìm min
$H=5x^2-x+1=5(x^2-\frac{x}{5})+1$
$=5[x^2-\frac{x}{5}+(\frac{1}{10})^2]+\frac{19}{20}$
$=5(x-\frac{1}{10})^2+\frac{19}{20}\geq \frac{19}{20}$
Vậy $H_{\min}=\frac{19}{20}$. Giá trị này đạt tại $x-\frac{1}{10}=0$
$\Leftrightarrow x=\frac{1}{10}$
tìm x
(3x + 2) x (3x- 2)- (3x- 1)^2= 5
\(\left(3x+2\right)\left(3x-2\right)-\left(3x-1\right)^2=5\)
\(\Leftrightarrow\left(9x^2-2^2\right)-\left(9x^2-6x+1\right)=5\)
\(\Leftrightarrow9x^2-4-9x^2+6x-1-5=0\)
\(\Leftrightarrow6x=10\)
\(\Leftrightarrow x=\dfrac{5}{3}\)
Vậy \(S=\left\{\dfrac{5}{3}\right\}\)
(3x + 2) . (3x- 2)- (3x- 1)^2= 5
<=> (3x + 2) . (3x- 2)- [ ( 3x^2 ) - 2 . 3x .1 + 1^2 ] = 5
<=> 9x^2 - 6x + 6x - 4 - ( 9x^2 - 6x + 1 ) = 5
<=> 9x^2 - 6x + 6x - 4 - 9x^2 + 6x - 1 = 5
<=> 6x - 5 = 5
<=> 6x = 5 + 5
<=> 6x = 10
<=> x = 10/6
<=> x = 5/3