Cho 4x 2 + 3x − 7 A = 4x + 7 x + 3 ( x ≠ − 3 ; x ≠ − 7 4 ) Khi đó đa thức A là?
A. A = x 2 + 2 x - 3
B. A = x 2 + 2 x + 3
C. A = x 2 - 2 x - 3
D. A = x 2 + 2 x
a. 2x + 3 chia hết cho 3x - 2
b. x.x + 4x +7 chia hết cho x + 2
c. / x - 2 / - / 4x - 8/ + /6 - 3x / = 32
a) (4x+1) (3x+7/3-5x. +1) = (x-4) (3x+7/5x-3. -1)
b) (x^2+3x+1) (4x-3/3x+1. +2)=(4x-7) (4x-3/3x+1. +2)
(+1; -1; +2 không phải mẫu nhé. Nó là 1 số riêng)
a)3x*(4x^2-x+7) b)(2x-1)*(4x+5) c)(12x^7-9x^5+6x^3)3x^2
a.4x^3-4x^2+x=0
b.x.(x-3)+12-4x=0
c.x^3+3x^2+3x-7=0
*tìm x*
c: Ta có: \(x^3+3x^2+3x-7=0\)
\(\Leftrightarrow x+1=2\)
hay x=1
b: Ta có: \(x\left(x-3\right)-4x+12=0\)
\(\Leftrightarrow\left(x-3\right)\left(x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)
Tìm GTNN
a) A= 4x^2+11x-2
b) B= 3x^2-2x-1
Tìm GTLN
a) A = -x^2+3x-1
b) B = -x^2-4x+7
a)A=4(x+11/8)^2 -153/16
Min A=-153/16 khi x=-11/8
b)B=3(x-1/3)^2 -4/3
Min B=-4/3 khi x=1/3
Bài 1:
a) \(A=4x^2+11x-2=\left(4x^2+11x+\dfrac{121}{16}\right)-\dfrac{153}{16}=\left(2x+\dfrac{11}{4}\right)^2-\dfrac{153}{16}\ge-\dfrac{153}{16}\)
\(minA=-\dfrac{153}{16}\Leftrightarrow x=-\dfrac{11}{8}\)
b) \(B=3x^2-2x-1=3\left(x^2-\dfrac{2}{3}x+\dfrac{1}{9}\right)-\dfrac{4}{3}=3\left(x-\dfrac{1}{3}\right)^2-\dfrac{4}{3}\ge-\dfrac{4}{3}\)
\(minB=-\dfrac{4}{3}\Leftrightarrow x=\dfrac{1}{3}\)
Bài 2:
a) \(A=-x^2+3x-1=-\left(x^2-3x+\dfrac{9}{4}\right)+\dfrac{5}{4}=-\left(x-\dfrac{3}{2}\right)^2+\dfrac{5}{4}\le\dfrac{5}{4}\)
\(maxA=\dfrac{5}{4}\Leftrightarrow x=\dfrac{3}{2}\)
b) \(B=-x^2-4x+7=-\left(x^2+4x+4\right)+11=-\left(x+2\right)^2+11\le11\)
\(maxB=11\Leftrightarrow x=-2\)
Bài 1:
a: Ta có: \(A=4x^2+11x-2\)
\(=4\left(x^2+\dfrac{11}{4}x-\dfrac{1}{2}\right)\)
\(=4\left(x^2+2\cdot x\cdot\dfrac{11}{8}+\dfrac{121}{64}-\dfrac{153}{64}\right)\)
\(=4\left(x+\dfrac{11}{8}\right)^2-\dfrac{153}{16}\ge-\dfrac{153}{16}\forall x\)
Dấu '=' xảy ra khi \(x=-\dfrac{11}{8}\)
b: Ta có: \(B=3x^2-2x-1\)
\(=3\left(x^2-\dfrac{2}{3}x-\dfrac{1}{3}\right)\)
\(=3\left(x^2-2\cdot x\cdot\dfrac{1}{3}+\dfrac{1}{9}-\dfrac{4}{9}\right)\)
\(=3\left(x-\dfrac{1}{3}\right)^2-\dfrac{4}{3}\ge-\dfrac{4}{3}\forall x\)
Dấu '=' xảy ra khi \(x=\dfrac{1}{3}\)
a, (4x^2 - 2)^2 = 196/81
b, (2x-4)^2016 + | x^2-4 | = 0
c, (7 - 3x)^2020 = (3x - 7)^2018
d, (4x - 7)^2 -5|7 - 4x| = 0
Giúp mik vs!
a) \(\left(4x^2-2\right)^2=\frac{196}{81}\)
<=> \(2^2\left(2x^2-1\right)^2=\frac{196}{81}\)
<=> \(4\left(2x^2-1\right)^2=\frac{196}{81}\)
<=> \(\left(2x^2-1\right)^2=\frac{196}{81}:4\)
<=> \(\left(2x^2-1\right)^2=\frac{49}{81}\)
<=> \(2x^2-1=\pm\sqrt{\frac{49}{81}}\)
<=> \(2x^2-1=\pm\frac{7}{9}\)
<=> \(\orbr{\begin{cases}2x^2-1=\frac{7}{9}\\2x^2-1=-\frac{7}{9}\end{cases}}\)<=> \(\orbr{\begin{cases}x=\pm\frac{2\sqrt{2}}{3}\\x=\pm\frac{1}{3}\end{cases}}\)
=> \(\orbr{\begin{cases}x=\pm\frac{2\sqrt{2}}{3}\\x=\pm\frac{1}{3}\end{cases}}\)
bài 2 : cho hai đa thức
A(x)=1/4x mũ 3 + 11/3x mũ 2 - 6x - 2/3x mũ 2 + 7/4x mũ 3 +2x +3
B(x)= 2x mũ 3 + 2x mũ 2 - 3x + 9
a, thu gọn và sắp xếp đa thức A(x) theo lũy thừa giảm dần của biến
\(A\left(x\right)=\dfrac{1}{4}x^3+\dfrac{11}{3}x^2-6x-\dfrac{2}{3}x^2+\dfrac{7}{4}x^3+2x+3\)
\(=\left(\dfrac{1}{4}x^3+\dfrac{7}{4}x^3\right)+\left(\dfrac{11}{3}x^2-\dfrac{2}{3}x^2\right)-\left(6x-2x\right)+3\)
\(=2x^3+3x^2-4x+3\)
Bài 1:
a) 7x –12 = 5x + 3
b) 2(3x –5) –7(x + 1) = 2
c) (1 –3x)^2= (4x –3)^2
d) (2x + 3)(4x –2) –2(2x + 1)^2= 12
Bài 2:
Cho biểu thứcA = (5x –3y + 1)(7x + 2y –2)
a) Tìm x sao cho với y = 2 thì A = 0
b) Tìm y sao cho với x = -2 thì A = 0
1.
a.\(\Leftrightarrow7x-5x=3+12\)
\(\Leftrightarrow2x=15\Leftrightarrow x=\dfrac{15}{2}\)
b.\(\Leftrightarrow6x-10-7x-7=2\)
\(\Leftrightarrow x=-19\)
c.\(\Leftrightarrow1-3x=4x-3\)
\(\Leftrightarrow7x=2\Leftrightarrow x=\dfrac{2}{7}\)
d.\(\Leftrightarrow8x^2-4x+12x-6-8x^2-8x-2=12\)
\(\Leftrightarrow-2=12\left(voli\right)\)
Thực hiện phép tính :
a/ (x - 1)^2 - (4x + 3) (2 - x)
b/ (15x^3y^2 - 6x^2y^3) : 3x^2y^2 = (15x^3y^2 : 3x^2y^2) - (6x^2y^3 : 3x^2y^2) = 5x - 2y
c/\(\dfrac{x+7}{x-7}\) - \(\dfrac{x-7}{x+7}\) +\(\dfrac{4x^2}{x^2-49}\)
a/ (x-1)2-(4x+3)(2-x)=x2-2x+1-(8x-4x2+6-3x)
=x2-2x+1-8x+4x2-6+3x=5x2-7x-6
b/ (15x3y2 - 6x2y3) : 3x2y2 = 5x - 2y
c/ \(\dfrac{x+7}{x-7}-\dfrac{x-7}{x+7}+\dfrac{4x^2}{x^2-49}\)=\(\dfrac{\left(x+7\right)^2-\left(x-7\right)^2+4x^2}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{x^2+14x+49-\left(x^2-14x+49\right)+4x^2}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{28x+4x^2}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{4x\left(x+7\right)}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{4x}{x-7}\)
Giải phương trình:
a) (x^2+3x+1).((4x-3)/(3x+1)+2)=(4x+7).((4x-3)/(3x+1)+2)
b) (x-1)/(x+2)-x/(x-2)=(5x-2)/(4-x^2)
thỏ_con
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