tính (rút gọn ) : 1/(9x-18)+(16-7x)/(72-18x)+5/(12x+24)
tính (rút gọn ) : 1/(9x-18)+(16-7x)/(72-18x)+5/(12x+24)
\(\dfrac{1}{9x-18}+\dfrac{16-7x}{72-18x}+\dfrac{5}{12x+24}\)
=\(\dfrac{\left(72-18x\right)\left(12x+24\right)}{\left(9x-18\right)\left(72-18x\right)\left(12x+24\right)}+\dfrac{\left(16-7x\right)\left(9x-18\right)\left(12x+24\right)}{\left(72-18x\right)\left(9x-18\right)\left(12x+24\right)}+\dfrac{5\left(9x-18\right)\left(72-18x\right)}{\left(12x+24\right)\left(9x-18\right)\left(72-18x\right)}\)
=\(\dfrac{\left(72-18x\right)\left(12x+24\right)+\left(16-7x\right)\left(9x-18\right)\left(12x+24\right)+5\left(9x-18\right)\left(72-18x\right)}{\left(9x-18\right)\left(72-18x\right)\left(12x+24\right)}\)
=\(\dfrac{-756x^3+702x^2+8316x-11664}{\left(9x-18\right)\left(72-18x\right)\left(12x+24\right)}\)
=
Ngô thừa ân cái đề nhìn rối quá bạn ơi , có thể viết rõ ra hơn được không !
a, \(\dfrac{1}{a+1}+\dfrac{2}{1-a}+\dfrac{5a-1}{a^2-1}\) b, \(\dfrac{1}{9x-18}+\dfrac{16-7x}{72-18x}+\dfrac{5}{12x-24}\)
\(a.\dfrac{1}{a+1}+\dfrac{2}{1-a}+\dfrac{5a-1}{a^2-1}\)
\(=\dfrac{1}{a+1}-\dfrac{2}{a-1}+\dfrac{5a-1}{a^2-1}\)
\(=\dfrac{a-1}{\left(a+1\right)\left(a-1\right)}-\dfrac{2\left(a+1\right)}{\left(a+1\right)\left(a-1\right)}+\dfrac{5a-1}{\left(a+1\right)\left(a-1\right)}\)
\(=\dfrac{a-1-2a-2+5a-1}{\left(a+1\right)\left(a-1\right)}\)
\(=\dfrac{4a-4}{\left(a+1\right)\left(a-1\right)}\)
\(=\dfrac{4}{a+1}\)
a, \(\dfrac{3}{2x+6}-\dfrac{x-6}{2x^2+6x}\)
b, \(\dfrac{x+2}{x-3}-\dfrac{x^2+6}{x^2-3x}\)
c, \(\dfrac{1}{9x-18}+\dfrac{16-7x}{72-18x}+\dfrac{5}{12x-24}\)
a.\(\dfrac{3}{2\left(x+3\right)}-\dfrac{x-6}{2x\left(x+3\right)}=\dfrac{3x-x+6}{2x\left(x+3\right)}=\dfrac{2x+6}{2x\left(x+3\right)}=\dfrac{1}{x}\)
Rút gọn phân số rồi quy đồng mẫu số các phân số:
a,3/9 và 16/24
b,17/51 và 18/90
c,5/10 và 15/45
d,42/63 và 64/72
\(a,\dfrac{3}{9}=\dfrac{1}{3}\\ \dfrac{16 }{24}=\dfrac{2}{3}\\ b,\dfrac{17}{51}=\dfrac{1}{3}=\dfrac{5}{15}\\ \dfrac{18}{90}=\dfrac{1}{5}=\dfrac{3}{15}\\ c,\dfrac{5}{10}=\dfrac{1}{2}=\dfrac{3}{6}\\ \dfrac{15}{45}=\dfrac{1}{3}=\dfrac{2}{6}\\ d,\dfrac{42}{63}=\dfrac{2}{3}=\dfrac{6}{9}\\ \dfrac{64}{72}=\dfrac{8}{9}\)
rút gọn biểu thức dưới đây : A= (3x+4) (9x^2- 12x +16) - ( 16+ 27x^30)
ngu ngu ngu ngu ngu ngu
giải các phương trình sau:
\(1,\sqrt{18x}-6\sqrt{\dfrac{2x}{9}}=3-\sqrt{\dfrac{x}{2}}\)
\(2,\sqrt{3x}-2\sqrt{12x}+\dfrac{1}{3}\sqrt{27x}=-4\)
3, \(3\sqrt{2x}+5\sqrt{8x}-20-\sqrt{18}=0\)
\(4,\sqrt{16x+16}-\sqrt{9x+9}=1\)
\(5,\sqrt{4\left(1-3x\right)}+\sqrt{9\left(1-3x\right)}=10\)
\(6,\dfrac{2}{3}\sqrt{x-3}+\dfrac{1}{6}\sqrt{x-3}-\sqrt{x-3}=\dfrac{-2}{3}\)
2: ĐKXĐ: x>=0
\(\sqrt{3x}-2\sqrt{12x}+\dfrac{1}{3}\cdot\sqrt{27x}=-4\)
=>\(\sqrt{3x}-2\cdot2\sqrt{3x}+\dfrac{1}{3}\cdot3\sqrt{3x}=-4\)
=>\(\sqrt{3x}-4\sqrt{3x}+\sqrt{3x}=-4\)
=>\(-2\sqrt{3x}=-4\)
=>\(\sqrt{3x}=2\)
=>3x=4
=>\(x=\dfrac{4}{3}\left(nhận\right)\)
3:
ĐKXĐ: x>=0
\(3\sqrt{2x}+5\sqrt{8x}-20-\sqrt{18}=0\)
=>\(3\sqrt{2x}+5\cdot2\sqrt{2x}-20-3\sqrt{2}=0\)
=>\(13\sqrt{2x}=20+3\sqrt{2}\)
=>\(\sqrt{2x}=\dfrac{20+3\sqrt{2}}{13}\)
=>\(2x=\dfrac{418+120\sqrt{2}}{169}\)
=>\(x=\dfrac{209+60\sqrt{2}}{169}\left(nhận\right)\)
4: ĐKXĐ: x>=-1
\(\sqrt{16x+16}-\sqrt{9x+9}=1\)
=>\(4\sqrt{x+1}-3\sqrt{x+1}=1\)
=>\(\sqrt{x+1}=1\)
=>x+1=1
=>x=0(nhận)
5: ĐKXĐ: x<=1/3
\(\sqrt{4\left(1-3x\right)}+\sqrt{9\left(1-3x\right)}=10\)
=>\(2\sqrt{1-3x}+3\sqrt{1-3x}=10\)
=>\(5\sqrt{1-3x}=10\)
=>\(\sqrt{1-3x}=2\)
=>1-3x=4
=>3x=1-4=-3
=>x=-3/3=-1(nhận)
6: ĐKXĐ: x>=3
\(\dfrac{2}{3}\sqrt{x-3}+\dfrac{1}{6}\sqrt{x-3}-\sqrt{x-3}=-\dfrac{2}{3}\)
=>\(\sqrt{x-3}\cdot\left(\dfrac{2}{3}+\dfrac{1}{6}-1\right)=-\dfrac{2}{3}\)
=>\(\sqrt{x-3}\cdot\dfrac{-1}{6}=-\dfrac{2}{3}\)
=>\(\sqrt{x-3}=\dfrac{2}{3}:\dfrac{1}{6}=\dfrac{2}{3}\cdot6=\dfrac{12}{3}=4\)
=>x-3=16
=>x=19(nhận)
18x - 19 = 21+8x
g)18- 4x = -20-6x
h)-15x - 24 = - 7x +32
i) 15x- 3(4x - 6) = - 12+ 36
k) -10 x - 27 = - 7x +33
m) -17 x - 24 = - 9x - 40
n) -23x + 25 = - 18x +75
p) - 5x+ 7( 2x-3) = 4( x - 4)
q)24- 6(3x + 1) = -5( 4x- 4 ) - 8
r) 18-4. (6-2x) = -3.(4x +5 ) - 11
s) - 5. ( 4x-5) - 14 = 6.(2 - 3x) - 10x-9
giúp mik với giải cả cách làm nhé
18x -19 = 21 + 8x
18 x - 8x = 21 + 19
10 x = 40
x =4
g) 18 -4x=-20-6x
-4x + 6x = -20 - 18
2x = -38
x= -19
k, -10 \(x\) - 27 = -7\(x\) + 33
-27 - 33 = -7\(x\) + 10\(x\)
3\(x\) = -60
\(x\) - 20
m, -17\(x\) - 24 = -9\(x\) - 40
-24 + 40 = -9\(x\) + 17\(x\)
8\(x\) = 16
\(x\) = 2
h)-15x -24 = 7x + 32
-15x - 7x = 32 + 24
-22x = 56
x = \(-\dfrac{14}{5}\)
i)15x -3(4x -6)=-12+36
15x - 12x + 18 = 24
3x + 18 = 24
3x = 24 - 18
3x = 6
x=2
18- 4x = -20-6x
h)-15 x 24 = - 7x +32
i) 15x- 3(4x - 6) = - 12+ 36
k) -10 x - 27 = - 7x +33
m) -17 x - 24 = - 9x - 40
n) -23 x 25 = - 18x +75
p) - 5x+ 7( 2x-3) = 4( x - 4)
q)24- 6(3x + 1) = -5( 4x- 4 ) - 8
r) 18-4. (6-2x) = -3.(4x +5 ) - 11
Jup mik pls
18 - 4\(x\) = -20 - 6\(x\)
-4\(x\) + 6\(x\) = - 20 - 18
2\(x\) = - 38
\(x\) = - 19
h, -15 \(\times\) 24 = -7\(x\) + 32
7\(x\) = 360 + 32
7\(x\) = 392
\(x\) = 392:7
\(x\) = 56
i, 15\(x\) -3.(4\(x\) - 6) = -12 + 36
15\(x\) - 12\(x\) + 18 = 24
3\(x\) = 24 - 18
3\(x\) = 6
\(x\) = 2
k, -10\(x\) - 27 = -7\(x\) + 33
-27 - 33 = -7\(x\) + 10\(x\)
3\(x\) = -60
\(x\) = -20
m, -17\(x\) - 24 = - 9\(x\) - 40
- 24 + 40 = -9\(x\) + 17\(x\)
8\(x\) = 16
\(x\) = 2
n, -23 \(\times\) 25 = -18\(x\) + 75
-575 = -18\(x\) + 75
18\(x\) = 575 + 75
18\(x\) = 650
\(x\) = \(\dfrac{325}{9}\)
bài 1
a) rút gọn biểu thức : A= 4√12+ 3√75 -5√48
b) giải phương trình :√x-2 -√9x-18 =16
a ⇒A=\(4\sqrt{4\times3}+3\sqrt{25\times3}-5\sqrt{16\times3}=8\sqrt{3}+15\sqrt{3}-20\sqrt{3}=3\sqrt{3}\)
b ĐKXĐ x≥2 ⇔\(\sqrt{x-2}+3\sqrt{x-2}=16\Leftrightarrow4\sqrt{x-2}=16\Leftrightarrow\sqrt{x-2}=4\Rightarrow x-2=16\Leftrightarrow x=18\)
a. \(A=4\sqrt{12}+3\sqrt{75}-5\sqrt{48}\)
\(=8\sqrt{3}+15\sqrt{3}-20\sqrt{3}\)
\(=3\sqrt{3}\)
b. \(\sqrt{x-2}-\sqrt{9x-18}=16\)
\(\Leftrightarrow\sqrt{x-2}-\sqrt{9\left(x-2\right)}=16\)
\(\Leftrightarrow\sqrt{x-2}-3\sqrt{x-2}=16\)
\(\Leftrightarrow-2\sqrt{x-2}=16\)
\(\Leftrightarrow\sqrt{x-2}=-8\) ( Vô lý )
Vậy PT vô nghiệm
a, 4\(\sqrt{12}+3\sqrt{75}-5\sqrt{48}\)
=\(8\sqrt{3}+15\sqrt{3}-20\sqrt{3}\)
= (8+15-20)\(\sqrt{3}\) = 3\(\sqrt{3}\)