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a: =>17x-5x-15-2x-5=0
=>10x-20=0
=>x=2
b: =>\(\dfrac{3x-6-5x-10}{\left(x+2\right)\left(x-2\right)}=\dfrac{11x+23}{\left(x+2\right)\left(x-2\right)}\)
=>11x+23=-2x-16
=>13x=-39
=>x=-3(nhận)
c: =>5x+7>=3x-3
=>2x>=-10
=>x>=-5
d: =>5(3x-1)=-2(x+1)
=>15x-5=-2x-2
=>17x=3
=>x=3/17
e: =>4x^2-1-4x^2-3x-2=0
=>-3x-3=0
=>x=-1
g: =>7x-5-8x+2-7<0
=>-x-10<0
=>x+10>0
=>x>-10
a: =>17x-5x-15-2x-5=0
=>10x-20=0
=>x=2
b: =>\(\dfrac{3x-6-5x-10}{\left(x+2\right)\left(x-2\right)}=\dfrac{11x+23}{\left(x+2\right)\left(x-2\right)}\)
=>11x+23=-2x-16
=>13x=-39
=>x=-3(nhận)
c: =>5x+7>=3x-3
=>2x>=-10
=>x>=-5
d: =>5(3x-1)=-2(x+1)
=>15x-5=-2x-2
=>17x=3
=>x=3/17
e: =>4x^2-1-4x^2-3x-2=0
=>-3x-3=0
=>x=-1
g: =>7x-5-8x+2-7<0
=>-x-10<0
=>x+10>0
=>x>-10
a) \(\left(3x-2\right)\left(\frac{10x\left(x+3\right)-7\left(4x-3\right)}{35}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3x-2=0\\-18x+51=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{2}{3}\\x=\frac{17}{6}\end{matrix}\right.\)
b)\(\left(3,3x-11\right)\left(\frac{3\left(7x+2\right)+10\left(1-3x\right)}{15}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{3}{10}\\x=\frac{16}{9}\end{matrix}\right.\)
\(a)PT\Leftrightarrow4x^2-9-4x^2+20x+3x=0.\\ \Leftrightarrow23x=9.\\ \Leftrightarrow x=\dfrac{9}{23}.\\ b)PT\Leftrightarrow\left(2x+1\right)\left(4x-3\right)-\left(2x+1\right)\left(2x-1\right)=0.\\\Leftrightarrow\left(2x+1\right)\left(4x-3-2x+1\right)=0.\\ \Leftrightarrow\left(2x+1\right)\left(2x-2\right)=0.\\ \Leftrightarrow\left(2x+1\right)\left(x-1\right)=0. \)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-1}{2}.\\x=1.\end{matrix}\right.\)
Áp dụng BĐT\(a^3+b^3+c^3=3abc\) ta có (cái này bạn phải cm mới được áp dụng\(\left(x^2+3x-4\right)^3+\left(3x^3+7x+4\right)^3-\left(4x^2+10x\right)^3=-3\left(x^2+3x-4\right)\left(3x^3+7x+4\right)\left(4x^2+10x\right)=0\)
Sau đó bạn chia 3 trường hợp ra rồi giải pt tìm x
k mk nha
Các bước giải:
b1: cho biểu thức =0
(4x+3)3+(5-7x)3+(3x-8)3=0
b2: Dùng hằng đẳng thức A3-B3 và A3+B3
b3: Chuyển đổi
Nhớ like nha
x + 3x + 4x + 3x + 1 = 0
⇒x + x + 2x + 2x + 2x + 2x + x + 1 = 0
⇒x x + 1 + 2x x + 1 + 2x x + 1 + x + 1 = 0 ⇒ x + 1 x + x + x + x + x + 1 = 0 ⇒ x + 1 x x + 1 + x x + 1 + x + 1 = 0 ⇒ x + 1 x + 1 x + x + 1 = 0 ⇒ x + 1 x + x + 1 = 0 ⇒ x + 1 = 0 vix̀ + x + 1 ≠ 0 ⇒x + 1 = 0 ⇒x = −1 vậy pt có No ......... 3 2x − 3 − 6 x − 3 = 5 4x + 3 − 17 ⇔ 30 10 2x − 3 − 30 5 x − 3 = 30 6 4x + 3 − 30 17.30 ⇔20x − 30 − 5x + 15 = 24x + 18 − 510 ⇔20x − 5x − 24x = 18 − 510 + 30 − 15
⇔− 9x = −477 ⇔x = 53
vậy pt có No........
\(x^4+3x^3+4x^2+3x+1=0\)
\(\Rightarrow x^4+x^3+2x^3+2x^2+2x^2+2x+x+1=0\)
\(\Rightarrow x^3\left(x+1\right)+2x^2\left(x+1\right)+2x\left(x+1\right)+\left(x+1\right)=0\)
\(\Rightarrow\left(x+1\right)\left(x^3+x^2+x^2+x+x+1\right)=0\)
\(\Rightarrow\left(x+1\right)\left[x^2\left(x+1\right)+x\left(x+1\right)+\left(x+1\right)\right]=0\)
\(\Rightarrow\left(x+1\right)\left(x+1\right)\left(x^2+x+1\right)=0\)
\(\Rightarrow\left(x+1\right)^2\left(x^2+x+1\right)=0\)
\(\Rightarrow\left(x+1\right)^2=0\left(vìx^2+x+1\ne0\right)\)
\(\Rightarrow x+1=0\)
\(\Rightarrow x=-1\)
vậy pt có No .........
\(\frac{2x-3}{3}-\frac{x-3}{6}=\frac{4x+3}{5}-17\)
\(\Leftrightarrow\frac{10\left(2x-3\right)}{30}-\frac{5\left(x-3\right)}{30}=\frac{6\left(4x+3\right)}{30}-\frac{17.30}{30}\)
\(\Leftrightarrow20x-30-5x+15=24x+18-510\)
\(\Leftrightarrow20x-5x-24x=18-510+30-15\)
\(\Leftrightarrow-9x=-477\)
\(\Leftrightarrow x=53\)
vậy pt có No........
a,<=>7x+3x≥13+5
<=>10x≥18
<=>x≥\(\frac{9}{5}\)
b,<=>9x2+4x-3≥9x2+12x+4
<=>(9x2+4x-3)-(9x2+12x+4)≥0
<=>-8x-7≥0
<=>-8x≥7
<=>x≤\(\frac{-7}{8}\)
c,<=>\(\frac{3x-5}{8}\)+\(\frac{2-10x}{8}\)<\(\frac{4}{8}\)
<=>3x-5+2-10x<4
<=>-7x-3<4
<=>-7x<7
<=>x>-1