10x+56-8=102+12x
giải phương trình : (x²-6x+8)(x²-10x+18)+12x-39=0
tìm x
12x-10x=5^8:5^4+(201)^0
12x - 10x = 5^8 : 5^4 + 201^0
2x = 5^4 + 1
2x = 625 + 1
2x = 626
x = 626 : 2
x = 313
\(12x-10x=5^8:5^4+201^0\)
\(\Rightarrow x\left(12-10\right)=5^4+1\)
\(\Rightarrow2x=625+1=626\)
\(\Rightarrow x=626:2=313\)
Vậy x = 313
a)√16 -√x2+3x =0
b)3x-1-√4x2-12x+9 =0
c)√2x2-10x+11 = √x2-6x+8
a:
ĐKXĐ: \(x^2+3x>=0\)
=>x(x+3)>=0
=>\(\left[{}\begin{matrix}x>=0\\x< =-3\end{matrix}\right.\)
\(\sqrt{16}-\sqrt{x^2+3x}=0\)
=>\(\sqrt{x^2+3x}=\sqrt{16}\)
=>x^2+3x=16
=>x^2+3x-16=0
\(\text{Δ}=3^2-4\cdot1\cdot\left(-16\right)=9+64=73>0\)
Do đó: Phương trình có 2 nghiệm phân biệt là:
\(\left\{{}\begin{matrix}x_1=\dfrac{-3-\sqrt{73}}{2}\\x_2=\dfrac{-3+\sqrt{73}}{2}\end{matrix}\right.\)
b:
ĐKXĐ: \(x\in R\)
\(3x-1-\sqrt{4x^2-12x+9}=0\)
=>\(\sqrt{\left(2x-3\right)^2}=3x-1\)
=>\(\left\{{}\begin{matrix}3x-1>=0\\\left(3x-1\right)^2=\left(2x-3\right)^2\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=\dfrac{1}{3}\\\left(3x-1-2x+3\right)\left(3x-1+2x-3\right)=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>=\dfrac{1}{3}\\\left(x+2\right)\left(5x-4\right)=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-2\left(loại\right)\\x=\dfrac{4}{5}\left(nhận\right)\end{matrix}\right.\)
c:
ĐKXĐ: \(\left\{{}\begin{matrix}x^2-6x+8>=0\\2x^2-10x+11>=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}\left[{}\begin{matrix}x>=4\\x< =2\end{matrix}\right.\\\left[{}\begin{matrix}x< =\dfrac{5-\sqrt{3}}{2}\\x>=\dfrac{5+\sqrt{3}}{2}\end{matrix}\right.\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x< =\dfrac{5-\sqrt{3}}{2}\\x>=4\end{matrix}\right.\)
\(\sqrt{2x^2-10x+11}=\sqrt{x^2-6x+8}\)
\(\Leftrightarrow2x^2-10x+11=x^2-6x+8\)
=>\(x^2-4x+3=0\)
=>(x-1)(x-3)=0
=>x=3(loại) hoặc x=1(nhận)
11/ 4x2 - 4x - 5
12/ 4x2 + 12x + 10x
13/ 4x2 - 12x - 5
14/ 9x2 + 12x + 8
tìm GTNN .cần gấp
\(4x^2-4x-5=4x^2-4x+1-6=\left(2x-1\right)^2-6\ge-6\)
\(Min=-6\Leftrightarrow x=\dfrac{1}{2}\)
\(4x^2+12x+10=4\left(x^2+3x+\dfrac{9}{4}\right)+1=4\left(x+\dfrac{3}{2}\right)^2+1\ge1\)
\(Min=1\Leftrightarrow x=-\dfrac{3}{2}\)
\(4x^2-12x-5=4\left(x^2-3x+\dfrac{9}{4}\right)-14=4\left(x-\dfrac{3}{2}\right)^2-14\ge-14\)
\(Min=-14\Leftrightarrow x=\dfrac{3}{2}\)
\(9x^2+12x+8=\left(9x^2+12x+4\right)+4=\left(3x+2\right)^2+4\ge4\)
\(Min=4\Leftrightarrow x=-\dfrac{2}{3}\)
Bài 1: Tìm x để biểu thức có nghĩa
a) \(\dfrac{-5}{\sqrt{10x+2}}\) d)\(\sqrt{\dfrac{3-12x}{-4}}\)
b) \(\sqrt{\dfrac{-5}{10x+2}}\) e)\(\sqrt{x^2+1}\)
c)\(\sqrt{\dfrac{8-4x}{10}}\) f) \(^{\dfrac{10}{\sqrt{2020-2021}}}\)
g) \(\sqrt{\dfrac{2x-8}{x^2+1}}\)
Giúp mk vs, sắp pk nộp r :<<
Thanks ạ
Tìm x:
1. ( 4x4 + 3x3 ) : ( -x3) + ( 15x2 + 6x ) : 3x = 0
2. ( 25x2 - 10x) : ( -5x) - 3( x-2) = 4
3. ( 42x3 - 12x ) : ( -6x) + 7x ( x+2) = 8
`1)<=> -4x-3 + 5x+ 2 =0`
`<=> 5x-4x = -2+3`
`<=> x =1`
`2)<=> -5x +2-3x+6 =4`
`<=> -5x-3x = 4-6-2`
`<=> -8x=-4`
`<=> x=1/2`
`3) <=> -7x^2 +2 +7x^2 +14x =8`
`<=> 14x +2 =8`
`<=> 14x = 6`
`<=> x=3/7`
Tính giá trị của biểu thức: A)x² - y² tại x - 1050 và y - 50 B)x³ - 6x² + 12x + 8 tại x - 102
b: \(=\left(x-2\right)^3=100^3=1000000\)
Tìm min, max
P = 2x2 + 12x + 8
Q = 10x - x2 + 3
a: \(=2\left(x^2+6x+4\right)\)
\(=2\left(x^2+6x+9-5\right)\)
\(=2\left(x+3\right)^2-10>=-10\)
Dấu = xảy ra khi x=-3
b: \(=-\left(x^2-10x-3\right)\)
\(=-\left(x^2-10x+25-28\right)\)
\(=-\left(x-5\right)^2+28< =28\)
Dấu = xảy ra khi x=5
Rút gọn các biểu thức sau:
a)64x^3-48x^2+12x-1
b)(10x-1)(100x^2+10x+1)-10x(10x-1)(10x+1)
a: \(=\left(4x-1\right)^3\)
b: \(=1000x^3-1-10x\left(100x^2-1\right)\)
\(=-1+10x\)