(x-3)^2-(x-3)*(x^2+3x+9)+9*(x+1)^2=15
Rút gọn
(x^4-3x^2+9).(x^2+3)-(3+x^2)
(x-3)^3-(x-3).(x^2+3x+9+6.(x+1)^2
Tìm x
(x-2)^3-(x-3).(x^2+3x+9)+6.(x+1)^2=49
(x+2).(x^2-2x+4-x.(x^2+2)=15
mọi người ơi giúp với tui đang cần gấp .Ai làm nhanh nhất thì tui sẽ h cho
Bài 2: Tìm x, biết: a) (x+2)(x² -2x+4)-x(x²+2)=15 b) (x-2)³-(x-4)(x² + 4x+16) + 6(x+1)=49 c) (x - 1)³ + (2 - x)(4 + 2x + x²)+ 3x(x + 2) = 16 d) (x - 3)³ - (x - 3)(x² + 3x + 9) + 9(x + 1)² = 15
a: Ta có: \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x^2+2\right)=15\)
\(\Leftrightarrow x^3+8-x^3-2x=15\)
\(\Leftrightarrow2x=-7\)
hay \(x=-\dfrac{7}{2}\)
b: Ta có: \(\left(x-2\right)^3-\left(x-4\right)\left(x^2+4x+16\right)+6\left(x+1\right)^2=49\)
\(\Leftrightarrow x^3-6x^2+12x-8-x^3+64+6\left(x+1\right)^2=49\)
\(\Leftrightarrow-6x^2+12x+56+6x^2+12x+6=49\)
\(\Leftrightarrow24x=-13\)
hay \(x=-\dfrac{13}{24}\)
1: 3/x+1 + 2/x+2 = 5x+4/x2+ 3x + 2
2: 2/3x + 1 - 15/6x2-x-1 = 3/2x - 1
3: 9/3x - 1 - 5-x/3x2-4x+1 = 4/x+ 1
4:5/x - 2 + 2/x+4 = 3x/x2 + 2x - 8
5: 4/x+6 + 1/x - 3 = 9/x2 + 3x - 18
6:x/x-3 - 2x2 +9/2x2 - 3x - 9= 1/2x + 3
\(\frac{3}{x+1}+\frac{2}{x+2}=\frac{5x+4}{x^2+3x+2}.\)ĐKXĐ: \(x\ne-1;-2\)
\(\Leftrightarrow\frac{3\left(x+2\right)}{\left(x+1\right)\left(x+2\right)}+\frac{2\left(x+1\right)}{\left(x+1\right)\left(x+2\right)}=\frac{5x+4}{\left(x+1\right)\left(x+2\right)}\)
\(\Leftrightarrow3x+6+2x+2=5x+4\)
\(\Leftrightarrow3x+2x-5x=-6-2+4\)
\(\Leftrightarrow0x=-4\)
=> PT vô nghiệm
\(2;\frac{2}{3x-1}-\frac{15}{6x^2-x-1}=\frac{3}{2x-1}\)
\(\Leftrightarrow\frac{2\left(2x-1\right)}{\left(2x-1\right)\left(3x-1\right)}-\frac{15}{6x^2+3x-2x-1}=\frac{3\left(3x-1\right)}{\left(2x-1\right)\left(3x-1\right)}\)
\(\Leftrightarrow\frac{4x-2-15}{\left(2x-1\right)\left(3x-1\right)}=\frac{9x-3}{\left(2x-1\right)\left(3x-1\right)}\)
\(\Leftrightarrow4x-2-15=9x-3\)
\(\Leftrightarrow4x-9x=2+15-3\)
\(\Leftrightarrow-5x=14\)
.....
mấy cái này mẫu nào dài cậu phân tích ra :
VD : câu 3 : \(3x^2-4x+1\)
\(=3x^2-3x-x+1\)
\(=3x\left(x-1\right)-\left(x-1\right)\)
\(=\left(3x-1\right)\left(x-1\right)\)
r bắt đầu giải PHương trình :)) Mấy câu còn lại tương tự
4; \(\frac{5}{x-2}+\frac{2}{x+4}=\frac{3x}{x^2+2x-8}.\)
\(\Leftrightarrow\frac{5\left(x+4\right)}{\left(x-2\right)\left(x+4\right)}+\frac{2\left(x-2\right)}{\left(x-2\right)\left(x+4\right)}=\frac{3x}{\left(x-2\right)\left(x+4\right)}\)
\(\Leftrightarrow5x+20+2x-4=3x\)
\(\Leftrightarrow4x=-16\Leftrightarrow x=-2\left(TM\right)\)
KL ::
\(5;\frac{4}{x+6}+\frac{1}{x-3}=\frac{9}{x^2+3x-18}\)
\(\Leftrightarrow\frac{4\left(x-3\right)}{\left(x+6\right)\left(x-3\right)}+\frac{x+6}{\left(x-3\right)\left(x+6\right)}=\frac{9}{\left(x-3\right)\left(x+6\right)}\)
\(\Leftrightarrow4x+x=3+9-6\)
\(\Leftrightarrow5x=6\Leftrightarrow x=\frac{6}{5}\)
Bài 1:tìm x
a,(x+1)^3+(2-x)(4+2x+x^2)+3x(x+2)=17
b,(x+2)(x^2-2x+4)-x(x^2-2)=15
c,(x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15
d,x(x-5)(x+5)-(x+2)(x^2-2x+4)=3
\(a,\left(x+1\right)^3+\left(2-x\right)\left(4+2x+x^2\right)+3x\left(x+2\right)=17\)\(\Leftrightarrow x^3+3x^2+3x+1+8-x^3+3x^2+6x-17=0\)\(\Leftrightarrow6x^2+9x-8=0\)
\(\Leftrightarrow x^2+\dfrac{3}{2}x-\dfrac{4}{3}=0\)
\(\Leftrightarrow\left(x^2+\dfrac{3}{2}x+\dfrac{9}{16}\right)-\dfrac{9}{16}-\dfrac{4}{3}=0\)
\(\Leftrightarrow\left(x+\dfrac{3}{4}\right)^2=\dfrac{91}{48}\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{3}{4}=\sqrt{\dfrac{91}{48}}\\x+\dfrac{3}{4}=-\sqrt{\dfrac{91}{48}}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{\dfrac{91}{48}}-\dfrac{3}{4}\\x=-\sqrt{\dfrac{91}{48}}-\dfrac{3}{4}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-9+\sqrt{273}}{12}\\x=-\dfrac{9+\sqrt{273}}{12}\end{matrix}\right.\)
b, \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x^2-2\right)=15\)
\(\Leftrightarrow x^3+8-x^3+2x-15=0\)
\(\Leftrightarrow2x=7\Rightarrow x=\dfrac{7}{2}\)
dùng hằng đẳng thức để làm nha. cần gấp, thanks nhìu
a) (x-1)^3+(2-x)(4+2x+x^2)+3x(x+2)=17
b) (x+2)(x^2-2x+4)-x(x^2-2)=15
c) (x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15
d) x(x-5)(x+5)-(x+2)(x^2-2x+4)=3
a,\(\Leftrightarrow\left(x-1\right)^3+\left(2-x\right)\left(4+2x+x^2\right)+3x\left(x+2\right)-17=0\)
\(\Leftrightarrow x^3-3x^2+3x-1+8-x^3+3x^2+6x-17=0\)
\(\Leftrightarrow9x-10=0\)
\(\Leftrightarrow x=\frac{10}{9}\)
b,\(\Leftrightarrow x^3+8-x^3+2x-15=0\)
\(\Leftrightarrow2x=7\)
\(\Leftrightarrow x=\frac{7}{2}\)
c,\(\Leftrightarrow x^3-9x^2+27x-27-x^3+27+9x^2+18x+1-15=0\)
\(\Leftrightarrow45x=14\)
\(\Leftrightarrow x=\frac{14}{45}\)
(x-3)3-(x-3)*(x2+3x+9)+9*(x+1)2=15
Tìm x biết:
a) ( x – 3 ) 3 – ( x – 3 ) ( x 2 + 3 x + 9 ) + 9 ( x + 1 ) 2 = 15;
b) x(x – 5)(x + 5) – (x + 2)( x 2 - 2x + 4) = 3.
a) Rút gọn VT = 45x + 8. Từ đó tìm được x = 2 15 .
b) Rút gọn VT = -25x – 8. Từ đó tìm được x = − 11 25 .
Giải các phương trình sau:
a) x^2 – 4x + 4 = 25
b) (5 – 2x)^2 – 16 = 0
c) (x – 3)^3 – (x – 3)(x^2 + 3x + 9) + 9(x + 1)^2 = 15
a) \(x^2-4x+4=25\\ \Rightarrow\left(x-2\right)^2=25\\ \Rightarrow\left[{}\begin{matrix}x-2=-5\\x-2=5\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-3\\x=7\end{matrix}\right.\)
b) \(\left(5-2x\right)^2-16=0\\ \Rightarrow\left(5-2x\right)^2=16\\ \Rightarrow\left[{}\begin{matrix}5-2x=-4\\5-2x=4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=4,5\\0,5\end{matrix}\right.\)
c) \(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+9\left(x+1\right)^2=15\\ \Rightarrow\left(x-3\right)^3-\left(x-3\right)^3+9\left(x+1\right)^2=15\\ \Rightarrow9\left(x+1\right)^2=15\\ \Rightarrow\left(x+1\right)^2=\dfrac{5}{3}\\ \Rightarrow\left[{}\begin{matrix}x+1=-\sqrt{\dfrac{5}{3}}\\x+1=\sqrt{\dfrac{5}{3}}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-\dfrac{3+\sqrt{15}}{3}\\x=\dfrac{-3+\sqrt{15}}{3}\end{matrix}\right.\)
a)\(\Leftrightarrow\)\(x^2-4x-21=0\)
\(\Leftrightarrow\)\(x^2-7x+3x-21=0\)
\(\Leftrightarrow\)\(x(x-7)+3(x-7)=0\)
\(\Leftrightarrow\)\((x-7)(x+3)=0\)
\(\Leftrightarrow\)\(\left[\begin{array}{} x=7\\ x=-3 \end{array} \right.\)
b)\(\Leftrightarrow\)\((5-2x)^2-4^2=0\)
\(\Leftrightarrow\)\((5-2x-4)(5-2x+4)=0\)
\(\Leftrightarrow\)\((-2x+1)(-2x+9)=0\)
\(\Leftrightarrow\)\(\left[\begin{array}{} x=\dfrac{1}{2}\\ x=\dfrac{9}{2} \end{array} \right.\)
c)\((x-3)^3-(x-3)(x^2+3x+9)+9(x+1)^2=15\)
\(\Leftrightarrow\)\(x^3-9x^2+27x-27-x^3+27+9x^2+18x+9-15=0\)
\(\Leftrightarrow\)\(45x-6=0\)
\(\Leftrightarrow\)\(x=\dfrac{2}{15}\)
tìm x
a)(x+3)(x2-3x+9)-x3=2x
b)(x-2)3-(x-3)(x2+3x+9)+6(x+1)2=15