tìm x.
a, 2x(x-5)-x(3+2x)=26
b, x(2x2-3)-2x2(5-2x)+8x2-4x3=7
Cho biểu thức P= 1+ 3/x2+5x+6 : ( 8x2/ 4x3-8x2 - 3x/ 3x2-12 -1/x+2)
A) Rút gọn P
B) Tìm các giá trị của x để P= 0; P= 1
C) Tìm cã giá trị của x để P> 0
Cho biểu thức
Q= (2x-x2/ 2x2 +8 - 2x2/ 3x3-2x2+4x-8) (2/x2 + 1-x/x)
A) Rút gọn Q
B) Tìm giá trị nguyên của x để Q có giá trị nguyên
Bài 1:
a) Ta có: \(P=1+\dfrac{3}{x^2+5x+6}:\left(\dfrac{8x^2}{4x^3-8x^2}-\dfrac{3x}{3x^2-12}-\dfrac{1}{x+2}\right)\)
\(=1+\dfrac{3}{\left(x+2\right)\left(x+3\right)}:\left(\dfrac{8x^2}{4x^2\left(x-2\right)}-\dfrac{3x}{3\left(x-2\right)\left(x+2\right)}-\dfrac{1}{x+2}\right)\)
\(=1+\dfrac{3}{\left(x+2\right)\left(x+3\right)}:\left(\dfrac{4}{x-2}-\dfrac{x}{\left(x-2\right)\left(x+2\right)}-\dfrac{1}{x+2}\right)\)
\(=1+\dfrac{3}{\left(x+2\right)\left(x+3\right)}:\dfrac{4\left(x+2\right)-x-\left(x-2\right)}{\left(x-2\right)\left(x+2\right)}\)
\(=1+\dfrac{3}{\left(x+2\right)\left(x+3\right)}\cdot\dfrac{\left(x-2\right)\left(x+2\right)}{4x+8-x-x+2}\)
\(=1+3\cdot\dfrac{\left(x-2\right)}{\left(x+3\right)\left(2x+10\right)}\)
\(=1+\dfrac{3\left(x-2\right)}{\left(x+3\right)\left(2x+10\right)}\)
\(=\dfrac{\left(x+3\right)\left(2x+10\right)+3\left(x-2\right)}{\left(x+3\right)\left(2x+10\right)}\)
\(=\dfrac{2x^2+10x+6x+30+3x-6}{\left(x+3\right)\left(2x+10\right)}\)
\(=\dfrac{2x^2+19x-6}{\left(x+3\right)\left(2x+10\right)}\)
Tìm x, biết:
a) 2(5x-8)-3(4x-5) = 4(3x-4) + 11;
b) 2 x ( 6 x - 2 x 2 ) + 3 x 2 ( x - 4 ) = 8;
c) 2 ( x 3 - 1 ) - 2 x 2 ( x + 2 x 4 ) + ( 4 x 5 + 4 ) x = 6;
d)(2x)2(4x-2)-(x3 -8x2) = 15.
a) x = 2 7 b) x = 2.
c) x = 2 d) x = 1.
1) Phân tích đa thức thành nhân tử
a) 2x4-4x3+2x2
b) 2x2-2xy+5x-5y
2) Tìm x, biết:
a) 4x(x-3)-x+3=0
b)(2x-3)2-(x+1)2=0
1.
a) \(2x^4-4x^3+2x^2\)
\(=2x^2\left(x^2-2x+1\right)\)
\(=2x^2\left(x-1\right)^2\)
b) \(2x^2-2xy+5x-5y\)
\(=\left(2x^2-2xy\right)+\left(5x-5y\right)\)
\(=2x\left(x-y\right)+5\left(x-y\right)\)
\(=\left(x-y\right)\cdot\left(2x+5\right)\)
2 .
a,
\(4x\left(x-3\right)-x+3=0\)
⇒\(4x\left(x-3\right)-\left(x-3\right)=0\)
⇒\(\left(x-3\right)\left(4x-1\right)=0\)
⇒\(\left[{}\begin{matrix}x-3=0\\4x-1=0\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=3\\4x=1\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=3\\x=\dfrac{1}{4}\end{matrix}\right.\)
vậy \(x\in\left\{3;\dfrac{1}{4}\right\}\)
b,
\(\)\(\left(2x-3\right)^2-\left(x+1\right)^2=0\)
⇒\(\left(2x-3-x-1\right)\left(2x-3+x+1\right)\) = 0
⇒\(\left(x-4\right)\left(3x-2\right)=0\)
⇔\(\left[{}\begin{matrix}x-4=0\\3x-2=0\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=4\\3x=2\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=4\\x=\dfrac{2}{3}\end{matrix}\right.\)
vậy \(x\in\left\{4;\dfrac{2}{3}\right\}\)
Cho đa thức A(x)= 2x-3x3+2x2+1 B(x)=4x3+2x2-5 tính A(x)+B(x) tính B(x) tại x=1 mình đang cần gấp giúp mình với
A(x)+B(x)=2x-3x3+2x2+1+4x3+2x2-5
= x3+4x2+2x-4
thay x=1 vào B(x) ta được
B(x)=4.13+2.13-5
=4+2-5
=1
\(A\left(x\right)+B\left(x\right)=\left(x+2\right)\left(x^2+2x-2\right)\)
thay x=1 \(=>A\left(1\right)+B\left(1\right)=3\left(1+2-2\right)=3\)
Ta có:
A(x)+B(x)=2x-3x³+2x²+1+4x³+2x²-5
=(-3x³+4x³)+(2x²+2x²)+2x+(1-5)
=x³+4x²+2x-4
Thay x=1 vào B(x) ta có:
B(1)=4*1³+2*1²-5
=4+2-5=1
Giải phương trình
e) x4 -4x3-8x2+8x=0
f) 2x2+3xy+y2=0
g) 2x4-x3-9x2+13x-5=0
h) (x+1)(x+3)(x+5)(x+7)+15=0
e: =>x(x^3-4x^2-8x+8)=0
=>x[(x^3+8)-4x(x+2)]=0
=>x(x+2)(x^2-2x+4-4x)=0
=>x(x+2)(x^2-6x+4)=0
=>\(x\in\left\{0;-2;3+\sqrt{5};3-\sqrt{5}\right\}\)
g: =>2x^4+5x^3-6x^3-15x^2+6x^2+15x-2x-5=0
=>(2x+5)(x^3-3x^2+3x-1)=0
=>(2x+5)(x-1)^3=0
=>x=1 hoặc x=-5/2
h: =>(x^2+8x+7)(x^2+8x+15)+15=0
=>(x^2+8x)^2+22(x^2+8x)+120=0
=>(x^2+8x+10)(x^2+8x+12)=0
=>(x^2+8x+10)(x+2)(x+6)=0
=>\(x\in\left\{-2;-6;-4+\sqrt{6};-4-\sqrt{6}\right\}\)
tìm x , biết
a, x ( x -1 ) - x2 + 2x = 5
b, 4x3 - 36x = 0
c, 2x2 - 2x = ( x - 1 )2
d, ( x - 7 ) ( x2- 9x + 20 ) ( x - 2 ) = 72
giúp emmm
a) \(\Leftrightarrow x^2-x-x^2+2x=5\)
\(\Leftrightarrow x=5\)
b) \(\Leftrightarrow4x\left(x^2-9\right)=0\)
\(\Leftrightarrow4x\left(x-3\right)\left(x+3\right)=0
\)
\(\Leftrightarrow\)\(\left[{}\begin{matrix}4x=0\\x-3=0\\x+3=0\end{matrix}\right.\)
\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=0\\x=3\\x=-3\end{matrix}\right.\)
Vậy x = 0 , x = 3 hoặc x = -3
\(a,\Leftrightarrow x^2-x-x^2+2x=5\\ \Leftrightarrow x=5\\ b,\Leftrightarrow4x\left(x^2-9\right)=0\\ \Leftrightarrow4x\left(x-3\right)\left(x+3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\\x=-3\end{matrix}\right.\\ c,\Leftrightarrow2x\left(x-1\right)-\left(x-1\right)^2=0\\ \Leftrightarrow\left(x-1\right)\left(2x-x+1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=1\\x=-1\end{matrix}\right.\\ d,\Leftrightarrow\left(x^2-9x+14\right)\left(x^2-9x+20\right)-72=0\\ \Leftrightarrow\left(x^2-9x+17\right)^2-3^2-72=0\\ \Leftrightarrow\left(x^2-9x+17\right)^2-81=0\\ \Leftrightarrow\left(x^2-9x+17-9\right)\left(x^2-9x+17+9\right)=0\\ \Leftrightarrow\left(x-8\right)\left(x-1\right)\left(x^2-9x+26\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=8\\x=1\\\left(x-\dfrac{9}{2}\right)^2+\dfrac{23}{4}=0\left(vô.n_0\right)\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=8\end{matrix}\right.\)
Tìm số nguyên x biết:
a) 12-(2x2-3)=7
b) 3x2-12=2x2+4
c) 2x-3.(2x+1)=4x-5.(x-3)
d) (x-2).(x+5)=0
Làm 1 câu bất kì cũng dc ạ!
a, 12 - (2\(x^2\) - 3) = 7
2\(x^2\) - 3 = 12 - 7
2\(x^2\) - 3 = 5
2\(x^2\) = 8
\(x^2\) = 4
\(\left[{}\begin{matrix}x=-2\\x=2\end{matrix}\right.\)
a) \(12-\left(2x^2-3\right)=7\\ 12-2x^2+3=7\\ 15-2x^2=7\\ 2x^2=15-7=8\\ x^2=8:2=4\\ x=\pm2\)
b) \(3x^2-12=2x^2+4\\ 3x^2-2x^2=12+4\\ x^2=16\\ x=\pm4\)
b, 3\(x^2\) - 12 = 2\(x^2\) + 4
3\(x^2\) - 2\(x^2\) = 12 + 4
\(x^2\) = 16
\(\left[{}\begin{matrix}x=-4\\x=4\end{matrix}\right.\)
Bài 5: Tìm nghiệm của các đa thức sau: Dạng 1: a) 4x + 9 b) -5x + 6 c) 7 – 2x d) 2x + 5 Dạng 2: a) ( x+ 5 ) ( x – 3) b) ( 2x – 6) ( x – 3) c) ( x – 2) ( 4x + 10 ) Dạng 3: a) x2 -2x b) x2 – 3x c) 3x2 – 4x d) ( 2x- 1)2 Dạng 4: a) x2 – 1 b) x2 – 9 c)– x 2 + 25 d) x2 - 2 e) 4x2 + 5 f) –x 2 – 16 g) - 4x4 – 25 Dạng 5: a) 2x2 – 5x + 3 b) 4x2 + 6x – 1 c) 2x2 + x – 1 d) 3x2 + 2x – 1
Số nghiệm của phương trình 2 x 2 + 2 x - 9 = ( x 2 - x - 3 ) . 8 x 2 + 3 x - 6 + ( x 2 + 3 x - 6 ) . 8 x 2 - x - 3 là:
A. 1
B. 3
C. 2
D. 4
Bài 4: Tìm số nguyên x biết:
a) 3x + 27 = 9 b) 2x + 12 = 3(x – 7)
c) 2x2 – 1 = 49 d) |-9 – x| -5 = 12
b) 2x + 12 = 3(x – 7)
d) |-9 – x| -5 = 12