tim x biet
a,|2x+1| = 3x-2
b,\(\frac{5}{x}\)=\(\frac{x}{25}\)
moi ng oi giup voi mai minh di hoc rui
tim so xyz biet \(\frac{x^2}{4}\)=\(\frac{y^2}{9}\)=\(\frac{z^2}{25}\)va x-y+xy=4
cac ban oi giup oi giup mk voi!!!
bai 1: cho phuong trinh: x2+(a+b).x-2.(a2-ab+b2) =0. CMR: luon co nghiem voi moi ab
cac ban oi giup minh sap di hoc roi.
Denta = (a + b )^2 - 4(-2(a^2 -ab + b^2))
= a^2 + ab+ b^2 +8a^2 -8ab + 8b^2
=9a^2 + 9b^2 - 7ab
=2( 4a^2 - 4ab + b^2 ) + (a^2 + ab + b^2/4) + 27/4
=2(2a - b)^2 + (a + b/2)^2 + 27/4 lớn hơn 0 với mọi a, b
Vậy pt luôn có nghiệm
a
Cac ban oi giup minh voi
tim x biet 6.4/x=x/99tim cac so nguyen biet (|x|-3)(x^2+4) be hon hoac bang 4hai dia diem a va b cach nhau 90kmhai nguoi di xe dap cung mot luc tu ava bde gap nhau va ho gap nhau cach a 50km;nhung neu nguoi di tu b di nhanh hon xuat phat truoc nguoi a 1 gio thi ho gap nhau cach a 350/9km tinh van toc moi nguoiCac giai ho minh voi minh se tick cho
Cac ban nho viet ho cach lam min voi
moi nguoi oi giup minh voi, ca cach giai nua nhe, dung thi minh se tich cho. thank you moi nguoi
tim x biet
x^2 - 1 < 15
Tim cac so nguyen x,y biet:a)*x2 -3*x+1 chia het cho x+2 b)x2-xy = 5x-4y-9 c) (x2-8)*(x2-15)<0 d) (x+1)2+(y+1)2+(x-y)2=2 e) (x2-4)x2>0 ai lam truoc minh tick,mai minh di hoc rui,lam giup minh di pls Thank ban truoc ne ;(
Giai phuong trinh:
\(\frac{x+10}{2000}+\frac{x+20}{1990}+\frac{x+30}{1980}+\frac{x+40}{1970}=-4\)
GIUP MINH VOI MAI MINH DI HOC ROI
\(\frac{x+10}{2000}+\frac{x+20}{1990}+\frac{x+30}{1980}+\frac{x+40}{1970}=-4\)
\(\Leftrightarrow\frac{x+10}{2000}+1+\frac{x+20}{1990}+1+\frac{x+30}{1980}+1+\frac{x+40}{1970}+1=0\)
\(\Leftrightarrow\frac{x+2010}{2000}+\frac{x+2010}{1990}+\frac{x+2010}{1980}+\frac{x+2010}{1970}=0\)
\(\Leftrightarrow\left(x+2010\right)\left(\frac{1}{2000}+\frac{1}{1990}+\frac{1}{1980}+\frac{1}{1970}\right)=0\)
Vì \(\frac{1}{2000}+\frac{1}{1990}+\frac{1}{1980}+\frac{1}{1970}>0\)
\(\Rightarrow x+2010=0\)
\(\Leftrightarrow x=-2010\)
\(\Leftrightarrow\frac{x+10}{2000}+1+\frac{x+20}{1990}+1+\frac{x+30}{1980}+1+\frac{x+40}{1970}+1=0\)
\(\Leftrightarrow\frac{x+2010}{2000}+\frac{x+2010}{1990}+\frac{x+2010}{1980}+\frac{x+2010}{1970}=0\)
\(\Leftrightarrow\left(x+2010\right)\left(\frac{1}{2000}+\frac{1}{1990}+\frac{1}{1980}+\frac{1}{1970}\right)=0\)
mà\(\left(\frac{1}{2000}+\frac{1}{1990}+\frac{1}{1980}+\frac{1}{1970}\right)\ne0\Rightarrow\left(x+2010\right)=0\\ \Rightarrow x=-2010\)
Giai phuong trinh
\(\frac{2}{x^2+4x+3}+\frac{2}{x^2+8x+15}+\frac{2}{x^2+12x+35}=\frac{2}{9}\)
GIUP MINH VOI MAI MINH DI HOC ROI
\(\frac{2}{\left(x+3\right)\left(x+1\right)}+\frac{2}{\left(x+3\right)\left(x+5\right)}+\frac{2}{\left(x+5\right)\left(x+7\right)}=\frac{2}{9}\)
\(\Rightarrow\frac{2}{x+1}-\frac{2}{x+3}+\frac{2}{x+3}-\frac{2}{x+5}+\frac{2}{x+5}-\frac{2}{x+7}=\frac{2}{9}\)
\(\frac{2}{x+1}-\frac{2}{x+7}=\frac{2}{9}\\ \Rightarrow\frac{2x+14-2x-2}{\left(x+1\right)\left(x+7\right)}=\frac{2}{9}\\ \Rightarrow\frac{12}{\left(x+1\right)\left(x+7\right)}=\frac{2}{9}=\frac{12}{54}\)
\(\Rightarrow\left(x+1\right)\left(x+7\right)=54\\ \Rightarrow x^2+8x-54=0\Rightarrow x=-4\pm\sqrt{70}\)
chết oy mk nhầm nha
\(\Rightarrow\frac{2}{\left(x+1\right)\left(x+3\right)}+\frac{2}{\left(x+3\right)\left(x+5\right)}+\frac{2}{\left(x+5\right)\left(x+7\right)}=\frac{2}{9}\Leftrightarrow\frac{1}{x+1}-\frac{1}{x+7}=\frac{2}{9}\)
\(\Rightarrow\frac{6}{\left(x+1\right)\left(x+7\right)}=\frac{2}{9}=\frac{6}{27}\\ \Rightarrow\left(x+1\right)\left(x+7\right)=27\)
\(\Rightarrow x^2+8x-20=0\Rightarrow\left(x-2\right)\left(x+10\right)=0\Rightarrow\orbr{\begin{cases}x=2\\x=-10\end{cases}}\)
sorry bạn nha mk nhầm xíu
Moi nguoi oi giup em gap vs:
tim x
a,6x^2-(2x-3)(3x+2)-1=0
b,(x-3)(x+7)-(x+5)(x-1)=0
moi nguoi co giup nhanh nhat co the ah!!
Ai trả lời câu này giúp em và nhỏ Vi với
a.\(6x^2-\left(2x-3\right)\left(3x+2\right)-1=0\Leftrightarrow6x^2-\left(6x^2-2x-6\right)-1=0\)
\(\Leftrightarrow2x+5=0\Leftrightarrow x=-\frac{5}{2}\)
b. \(\left(x-3\right)\left(x+7\right)-\left(x+5\right)\left(x-1\right)=0\Leftrightarrow x^2+4x-21-\left(x^2+4x-5\right)=0\)
\(\Leftrightarrow-16=0\)
Vậy không có x thỏa mãn.
Bài 1: cho x,y thoả mãn 0<x<2 và 4<y<5 và x+y=6
Tìm Min của P= \(\frac{1}{x}+\frac{1}{y}\)
cac ban oi giup minh di minh chuan bi di hoc roi. giup minh nhe.