(2x - 3) . 4,8 = ( 3x + 1 ) . (-2,4)
mn ơi, giúp mik vs nhanh hộ mik nha <3
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12 tháng 6 2023
2:
=>x^3-1-2x^3-4x^6+4x^6+4x=6
=>-x^3+4x-7=0
=>x=-2,59
4: =>8x-24x^2+2-6x+24x^2-60x-4x+10=-50
=>-62x+12=-50
=>x=1
KC
2
17 tháng 10 2023
1: \(75^3:\left(-25\right)^3=\left(\dfrac{75}{-25}\right)^3=\left(-3\right)^3=-27\)
2: \(\left(-60\right)^2:\left(-5\right)^2=\dfrac{60^2}{5^2}=12^2=144\)
3: \(169^2:\left(-13\right)^2=\dfrac{169^2}{13^2}=\left(\dfrac{169}{13}\right)^2=13^2=169\)
4: \(\left(\dfrac{1}{2}\right)^2:\left(\dfrac{3}{2}\right)^2=\left(\dfrac{1}{2}:\dfrac{3}{2}\right)^2=\left(\dfrac{1}{3}\right)^2=\dfrac{1}{9}\)
5: \(\left(\dfrac{2}{3}\right)^3:\left(\dfrac{8}{27}\right)^3=\left(\dfrac{2}{3}:\dfrac{8}{27}\right)^3=\left(\dfrac{2}{3}\cdot\dfrac{27}{8}\right)^3=\left(\dfrac{9}{4}\right)^3=\dfrac{729}{64}\)
6: \(\left(\dfrac{5}{4}\right)^4:\left(\dfrac{15}{2}\right)^4=\left(\dfrac{5}{4}:\dfrac{15}{2}\right)^4=\left(\dfrac{5}{4}\cdot\dfrac{2}{15}\right)^4=\left(\dfrac{1}{6}\right)^4=\dfrac{1}{1296}\)
7: \(\left(\dfrac{7}{8}\right)^5:\left(\dfrac{21}{16}\right)^5\)
\(=\left(\dfrac{7}{8}:\dfrac{21}{16}\right)^5\)
\(=\left(\dfrac{7}{8}\cdot\dfrac{16}{21}\right)^5=\left(\dfrac{2}{3}\right)^5=\dfrac{32}{243}\)
8: \(\left(\dfrac{5}{6}\right)^4:\left(\dfrac{25}{18}\right)^4=\left(\dfrac{5}{6}:\dfrac{25}{18}\right)^4=\left(\dfrac{5}{6}\cdot\dfrac{18}{25}\right)^4=\left(\dfrac{3}{5}\right)^4=\dfrac{81}{625}\)
9:
\(\left(-\dfrac{3}{4}\right)^3:\left(\dfrac{9}{8}\right)^3=\left(-\dfrac{3}{4}:\dfrac{9}{8}\right)^3=\left(-\dfrac{3}{4}\cdot\dfrac{8}{9}\right)^3\)
\(=\left(-\dfrac{2}{3}\right)^3=-\dfrac{8}{27}\)
10:
\(\left(\dfrac{9}{10}\right)^6:\left(\dfrac{27}{-20}\right)^6=\left(\dfrac{9}{10}:\dfrac{-27}{20}\right)^6\)
\(=\left(\dfrac{9}{10}\cdot\dfrac{20}{-27}\right)^6=\left(-\dfrac{2}{3}\right)^6=\dfrac{64}{729}\)
LM
2
YN
20 tháng 9 2021
\(B=\left|2x+3,5\right|+\left|2x+\frac{7}{2}\right|\)
\(=\left|3,5-2x\right|+\left|2x+3,5\right|\ge\left|3,5-2x+2x+3,5\right|=7\)
Dấu '' = '' xảy ra khi \(\left(3,5-2x\right)\left(2x+3,5\right)\ge0\)
\(\Rightarrow\orbr{\begin{cases}3,5-2x\ge0;2x+3,5\ge0\\3,5-2x\le0;2x+3,5\le0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}2x\le3,5;2x\ge-3,5\\2x\ge3,5;2x\le-3,5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x\le1,75;x\ge-1,75\Rightarrow-1,75\le x\le1,75\\x\ge1,75;x\le-1,75\text{(Vô lý)}\end{cases}}\)
Vậy \(MinB=7\Leftrightarrow-1,75\le x\le1,75\)
24 tháng 8 2018
4) (3x-2)(x-3)= 3x(x-3)-2(x-3)
=3x.x+3x.(-3)-2.x-2.(-3)
=\(3x^2\)-9x-4x+6
=\(3x^2\)+(-9x-4x)+6
=\(3x^2\)-13x+6
5) (2x+1)(x+3)=2x(x+3)+1(x+3)
=2x.x+2x.3+1.x+1.3
=\(2x^2\)+6x+1x+3
=\(2x^2\)+(6x+1x)+3
=\(2x^2\)+7x+3
6) (x-3)(3x-1)=x(3x-1)-3(3x-1)
=x.3x+x.(-1)-3.3x-3.(-1)
=\(3x^2\)-1x-9x+3
=\(3x^2\)+(-1x-9x)+3
=\(3x^2\)-10x+3
rút gọn biểu thức
A) \(x^2\)-(x+4)(x-1)=\(x^2\)- x(x-1)-4(x-1)
=\(x^2\)-x.x-x.(-1)-4.x-4.(-1)
=\(x^2\)-\(x^2\)+1x-4x+4
=(\(x^2-x^2\))+(1x-4x)+4
= -3x+4
B) x(x+2)-(x-2)(x+4)=x.x+x.2-x(x+4)+2(x+4)
=\(x^2+2x\)-x.x-x.4+2.x+2.4
=\(x^2+2x-x^2-4x+2x+8\)
=(\(x^2-x^2\))+(2x-4x+2x)+8
=8
tính giá trị biểu thức
A=3(x-2)-(2+x)(x-3)
=3.x+3.(-2)-2(x-3)-x(x-3)
=3x-6-2.x-2.(-3)-x.x-x(-3)
=3x-6-2x+6-\(x^2\)+3x
=(3x-2x+3x)+(-6+6)\(-x^2\)
=4x - \(x^2\)
thay x=-8 vào biểu thức thu gọn ta được:
4.(-8)- (-8)\(^2\)
= - 32 +64
= 32
B= x(3-x)-(1+x)(1-x)
=x.3+x.(-x)-1(1-x)-x(1-x)
=3x -\(x^2\)-1.1-1 .(-x)-x.1-x.(-x)
=3x\(-x^2\)-\(1^2\)+1x-1x+\(x^2\)
=(3x+1x-1x)+(\(-x^2+x^2\))-1
=3x-1
thay x=-5 vào biểu thức thu gọn ta được:
3.(-5)-1
=-15-1
=-16
24 tháng 8 2018
Thu gọn biểu thức
4) (3x - 2) (x - 3)
= ( 3x2 - 2x ) - ( 3x x 3 - 2 x 3 )
= 3x2 - 2x - 3x x 3 + 2 x 3
= 3x2 - 2x - 9x + 6
= 3x2 - 11x + 6
5) (2x + 1) (x + 3)
= ( 2x2 + 1x ) + ( 6x + 3 )
= 2x2 + 1x + 6x + 3
= 2x2 + 7x + 3
6) (x - 3) (3x - 1)
= ( 3x2 - 9x ) - ( x - 3 )
= 3x2 - 9x - x + 3
= 3x2 - 10 + 3
Rút gọn biểu thức
A) x^2 - (x + 4) (x - 1)
= x2 - ( x2 + 4x ) - ( x + 4 )
= x2 - x2 - 4x - x - 4
= -5x - 4
B) x (x + 2) - (x - 2) (x + 4)
= x2 + 2x - ( x2 - 2x ) + ( 4x - 8 )
= x2 + 2x - x2 + 2x + 4x - 8
= 8x - 8
Tính giá trị biểu thức
A = 3 (x - 2) - (2 + x) (x - 3) tại x = - 8
Thế x = -8 vào, ta có :
= 3 ( -8 -2 ) - ( 2 + -8 ) ( -8 - 3 )
= 3 x ( -10 ) - ( - 6 ) ( -11 )
= -30 - 66
= -96
B = x (3 - x) - (1 + x) ( 1 - x) tại x = - 5
Thế x = - 5 vào, ta có :
= -5 ( 3 - -5 ) - ( 1+ -5 ) ( 1 - -5 )
= -5 x 8 - (-4) x 6
= - 40 - -24
= -40 + 24
= -16
100% đúng
hok tốt nha
28 tháng 6 2023
a: =3/2-2/3:(4/18+3/18)
=3/2-2/3:7/18
=3/2-2/3*18/7
=3/2-12/7
=-3/14
b: =(5/8-1/5)*2-1/4
=5/4-2/5-1/4
=1-2/5=3/5
c: =(3+5/6-1/2):55/12
=10/3*12/55
=8/11
\(\left(2x-3\right)\cdot4,8=\left(3x+1\right)\cdot\left(-2,4\right)\)
\(9,6x-14,4=-7,2x-2,4\)
\(9,6x+7,2x=14,4-2,4\)
\(16,8x=12\)
\(x=\dfrac{12}{16,8}=\dfrac{5}{7}\)
x = 5/7