tìmx biết:
a)(x+1)+(x+3)+(x+5)+....(x+99)=0
b)(x-3)+(x-2)+(x-1)+...+10+11=11
giup mk voi .mk dang can gấp .
please.
a) 1-23+33+........+103=(x+1)2
b) 1+3+5+.............+99=(x-2)2
Cac ban oi giup mk voi mk dang can gap
a: Sửa đề: 1+2^3+3^3+...+10^3=(x+1)^2
=>(x+1)^2=(1+2+3+...+10)^2=55^2
=>x+1=55
=>x=54
b: Số số hạng là:
(99-1):2+1=50 số
Tổng là (99+1)*50/2=50^2
=>(x-2)^2=50^2
=>x-2=50
=>x=52
Bài 1:Tìm x biết:
a.,2x(x-3)-15+5x=0
b,x^3-7x
c,(2x-3)^2-(x+5)^2=0
d,x^3-x^2-4x^2+8x-4=0
giúp mk với mk cầm gấp lắm TvT
a, \(2x\left(x-3\right)-15+5x=0\\ \Rightarrow2x\left(x-3\right)-\left(15-5x\right)=0\\ \Rightarrow2x\left(x-3\right)-5\left(3-x\right)=0\\ \Rightarrow\left(2x+5\right)\left(x-3\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=-\dfrac{5}{2}\\x=3\end{matrix}\right.\)
b, \(x^3-7x=0\\ \Rightarrow x\left(x^2-7\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=\pm7\end{matrix}\right.\)
c, \(\left(2x-3\right)^2-\left(x+5\right)^2=0\\ \Rightarrow\left(2x-3-x-5\right)\left(2x-3+x+5\right)=0\\ \Rightarrow\left(x-8\right)\left(3x+2\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=8\\x=-\dfrac{2}{3}\end{matrix}\right.\)
Xem lại đề câu d
Tìm x, biết:
a)9x2–6x–3 = 0
b) (2x + 1)2–4(x + 2)2= 9
c)3(x –1)2–3x(x –5) = 21
d) (x + 3)2–(x –4)(x + 8) = 1
giúp mk với ạ
a. 9x2 - 6x - 3 = 0
<=> 3(3x2 - 2x - 1) = 0
<=> 3(3x2 - 3x + x - 1) = 0
<=> \(3\left[3x\left(x-1\right)+\left(x-1\right)\right]=0\)
<=> 3(3x + 1)(x - 1) = 0
<=> \(\left[{}\begin{matrix}3x+1=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-1}{3}\\x=1\end{matrix}\right.\)
b. (2x + 1)2 - 4(x + 2)2 = 9
<=> (2x + 1)2 - \(\left[2\left(x+2\right)\right]^2=9\)
<=> (2x + 1 - 2x - 4)(2x + 1 + 2x + 4) = 9
<=> -3(4x + 5) = 9
<=> 4x + 5 = -3
<=> 5 + 3 = -4x
<=> -4x = 8
<=> -x = 2
<=> x = -2
a) \(\Leftrightarrow\left(9x^2-6x+1\right)-4=0\)
\(\Leftrightarrow\left(3x-1\right)^2-4=0\)
\(\Leftrightarrow3\left(x-1\right)\left(3x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{1}{3}\end{matrix}\right.\)
b) \(\Leftrightarrow4x^2+4x+1-4x^2-16x-16=9\)
\(\Leftrightarrow12x=-24\Leftrightarrow x=-2\)
c) \(\Leftrightarrow3x^2-6x+3-3x^2+15x=21\)
\(\Leftrightarrow9x=18\Leftrightarrow x=2\)
d) \(\Leftrightarrow x^2+6x+9-x^2-4x+32=1\)
\(\Leftrightarrow2x=-40\Leftrightarrow x=-20\)
tim x biet N thuoc
a) 2-(x+3)=1+2+3+4+5+..............+99
b)(x+1)+(x+2)+(x+3)+(x+4)+...............+(x+100)=5750
giup mk nha cac ban , mk dang can gap lam
a) 2-(x+3) = 1+2+3+...+99
1+2+3+...+99 → có 99 số hạng
2-(x+3) = (1+99).99 : 2
2-(x+3) = 4950
x+3 = 2 + 4950
x+3 = 4952
x = 4952 - 3
x = 4949
b) (x+1)+(x+2)+...+(x+100) = 5750
→ có 100 cặp
(x+x+x+...+x) + ( 1+2+3+...+100 ) = 5750
=> 100x + 5050 = 5750
100x = 5750 - 5050
100x = 700
x = 700 : 100
x = 7
0o0 Nguyễn Đoàn Tuyết Vy 0o0 bà kêu tui học tốt có nghĩa là học giốt đúng ko
b)(x+1)+(x+2)+(x+3)+(x+4)+...............+(x+100)=5750
(x+x+x+x+...+x) + (1+2+3+4+...+100) = 5750
100x + 5050 = 5750
100x = 5750 - 5050
100x = 700
x = 700 : 100
x = 7
Vậy ...
Tìm x biết:
a) x(x-3)+2x-6=0
b) (x+1)2-4(x+1)=0
c) (2x+5)(4x+3)-8x(x+3)=10
a: \(x\left(x-3\right)+2x-6=0\)
\(\Leftrightarrow\left(x-3\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
b: \(\left(x+1\right)^2-4\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=3\end{matrix}\right.\)
tim gtnn , gtln của /x-can2/+/y-1/ voi /x/+/y/=5...ho mk voi,mk dang can gap
f(x) = 2 (x^3 - x) + x^2 - 3x + 3 - x^3
a) Thu gon hai da thuc tren roi xep theo luy thua giam dan cua bien
b) Tinh f(-1);g (1/2)
c) Tim f(x) + g(x);f(x) - g(x)
d) Tim gia tri cua x de f(x) = g(x) (giup mk voi mk dang can gap)
bai 1: Tim x
a) (x-1)^3 =27
b ( 2x +1)^2=25
c) (x-1)^x+2=(x-1)x+4
d) ( 2x-1)^3 =-8
e) 2^2x-2x=96
GIUP MK VOI NHA MK DANG CAN GAP LAM
Tìm x,biết:
a)5x.(x+1)-5.(x+1).(x-2)=0
b)(4x+1).(x-2)-(2x-3)2=4
a)5(x+1)(x-x-2)=0
=>5(x+1).-2=0
=>5(x+1)=0
=>x+1=0
=>x=-1
a)5x.(x+1)-5.(x+1).(x-2)=0
⇒5x(x+1)-(5x-10)(x+1)=0
⇒(x+1)(5x-5x+10)=0
⇒10(x+1)=0
⇒x+1=0⇒x=-1
a) \(5x\left(x+1\right)-5\left(x+1\right)\left(x-2\right)=0\)
\(\Leftrightarrow5\left(x+1\right)\left(x-x+2\right)=0\)
\(\Leftrightarrow10\left(x+1\right)=0\)
\(\Leftrightarrow x+1=0\Leftrightarrow x=-1\)
b) \(\left(4x+1\right)\left(x-2\right)-\left(2x-3\right)^2=4\)
\(\Leftrightarrow4x^2-7x-2-4x^2+12x-9=4\)
\(\Leftrightarrow5x=15\Leftrightarrow x=3\)