Cho A= 3(2x-3)(3x+2)-(2x+4)(4x-3)+9x(4-x). Tim gia tri cua x de A=0
Những câu hỏi liên quan
2(2x-3)(3x+2)-2(x+4)(4x-3)+9x(4-x)-6=0 voi gia tri nao cua x thi bt da cho co gt bang 0
\(2\left(2x-3\right)\left(3x+2\right)-2\left(x-4\right)\left(4x-3\right)+9x\left(4-x\right)-6=0\)
<=> \(2\left(6x^2-5x-6\right)-2\left(4x^2+13x-12\right)+25x-9x^2-6=0\)
<=> \(12x^2-10x-12-4x^2-26x+24+25x-9x^2-6=0\)
<=>\(-x^2-11x+6=0\)
<=>\(\left[\begin{array}{nghiempt}x=\frac{-11+\sqrt{145}}{2}\\x=\frac{-11-\sqrt{145}}{2}\end{array}\right.\)
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bạn có thể giảng giúp tớ được không ạ ???? cảm ơn nhiều nhak
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bai 1
a = (3x / 2x + 4 ) + (x +3 /x ^ 2 - 4 )
a . tim x de gia tri phan thuc a duoc xac dinh
b. rut gon a
c. tinh gia trin cua a khi x bang -3
d . tim gia tri cua x de phan thuc co gia tri bang 2
bai 1
a = (3x / 2x + 4 ) + (x +3 /x ^ 2 - 4 )
a . tim x de gia tri phan thuc a duoc xac dinh
b. rut gon a
c. tinh gia trin cua a khi x bang -3
d . tim gia tri cua x de phan thuc co gia tri bang 2
a: ĐKXĐ: x<>2; x<>-2
b: \(A=\dfrac{3x\left(x-2\right)+2x+6}{2\left(x-2\right)\left(x+2\right)}=\dfrac{3x^2-6x+2x+6}{2\left(x-2\right)\left(x+2\right)}\)
\(=\dfrac{3x^2+4x+6}{2\left(x-2\right)\left(x+2\right)}\)
c: Khi x=-3 thì \(A=\dfrac{3\cdot\left(-3\right)^2-4\cdot3+6}{2\left(-3-2\right)\left(-3+2\right)}=\dfrac{21}{10}\)
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Tim x de gia tri cua cac bieu thuc sau =0
a. x^3-x^2-4x-4
b. x^3-x^2+2x-2
c. x^3+6x^2+11x+6
b: \(\Leftrightarrow x^2\left(x-1\right)+2\left(x-1\right)=0\)
=>x-1=0
=>x=1
c: \(\Leftrightarrow x^3+x^2+5x^2+5x+6x+6=0\)
\(\Leftrightarrow\left(x+1\right)\left(x^2+5x+6\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(x+2\right)\left(x+3\right)=0\)
hay \(x\in\left\{-1;-3;-2\right\}\)
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Bai1:
a- 3x^2 - 7x +2 b- a(x^2 +1 ) - x (a^2 +1)
Bai2 : Cho bieu thuc
A= (2+x/ 2-x - 4x^2 / x^2 -4 - 2-x/ 2+x ) : x^2 - 3x / 2x^2 - x ^3
a- Tim DKXD roi rut gon bieu thuc A ?
b- Tim gia tri cua x de A>0?
c- Tinh gia tri cua A TRong truong hop : \vbar x-7 \vbar=4
Giup mk nha moi nguoi !!!!!!!!!
Bài 2:
a: ĐKXĐ: \(x\notin\left\{0;2;-2;3\right\}\)\(A=\left(\dfrac{-\left(x+2\right)}{x-2}-\dfrac{4x^2}{\left(x-2\right)\left(x+2\right)}+\dfrac{x-2}{x+2}\right):\dfrac{x\left(x-3\right)}{x^2\left(2-x\right)}\)
\(=\dfrac{-x^2-4x-4-4x^2+x^2-4x+4}{\left(x-2\right)\left(x+2\right)}\cdot\dfrac{-x\left(x-2\right)}{x-3}\)
\(=\dfrac{-4x^2-8x}{\left(x+2\right)}\cdot\dfrac{-x}{x-3}\)
\(=\dfrac{-4x\left(x+2\right)}{x+2}\cdot\dfrac{-x}{x-3}=\dfrac{4x^2}{x-3}\)
b: Để A>0 thì x-3>0
hay x>3
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cho bieu thuc
P\(\left(x\right)=\dfrac{20x^2+120x+180}{\left(3x+5\right)^2-4x^2}+\dfrac{5x^2-125}{9x^2-\left(2x+5\right)^2}-\dfrac{\left(2x+3\right)^2-x^2}{3\left(x^2+8x+15\right)}\)
Tim gia tri nguyen cua x de P(x) co gia tri nguyen
\(P=\dfrac{20\left(x^2+6x+9\right)}{\left(3x+5+2x\right)\left(3x+5-2x\right)}+\dfrac{5\left(x-5\right)\left(x+5\right)}{\left(3x-2x-5\right)\left(3x+2x+5\right)}-\dfrac{\left(2x+3+x\right)\left(2x+3-x\right)}{3\left(x+3\right)\left(x+5\right)}\)
\(=\dfrac{20\left(x+3\right)^2}{5\left(x+1\right)\left(x+5\right)}+\dfrac{5\left(x-5\right)\left(x+5\right)}{\left(x-5\right)\cdot5\left(x+1\right)}-\dfrac{3\left(x+1\right)\left(x+3\right)}{3\left(x+3\right)\left(x+5\right)}\)
\(=\dfrac{5\left(x+3\right)^2}{\left(x+1\right)\left(x+5\right)}+\dfrac{\left(x+5\right)}{x+1}-\dfrac{x+1}{x+5}\)
\(=\dfrac{5x^2+30x+45+x^2+10x+25-x^2-2x-1}{\left(x+5\right)\left(x+1\right)}\)
\(=\dfrac{5x^2+38x+69}{\left(x+5\right)\left(x+1\right)}\)
\(=\dfrac{5x^2+38x+69}{x^2+6x+5}\)
Để P là số nguyên thì \(5x^2+30x+25+8x+34⋮x^2+6x+5\)
=>\(8x+34⋮x^2+6x+5\)
=>\(\left\{{}\begin{matrix}8x+34⋮x+1\\8x+34⋮x+5\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}8x+8+26⋮x+1\\8x+40-6⋮x+5\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x+1\in\left\{1;-1;2;-2;13;-13;26;-26\right\}\\x+5\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\end{matrix}\right.\)
=>\(x\in\left\{-2;1\right\}\)
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Tim cac gia tri nguyen cua x de cac gia tri bieu thuc sau la so nguyen
a, 9-2x/x-3
b,3x-5/x-2
c,-3/4-x
tim cac gia tri cua x de bieu thuc sau nhan gia tri duong
a) x mu 2 + 4x b)2x mu 2 - 4x c)(x-3)(x+7) d)5(3x +1 )(4x-3) e)(1/2-x)(1/3-x)
cho P=(2+x/2-x+4x^2/x^2-4-2-x/2+x):x^2-3x/2x^2-x^3
a) tim dieu kien cua x de gia tri cua P xac dinh
b) rut gon P
mn giup minh voi