Tim x biet
a) x-2 trên 5=3phan8
Tim so nguyen x,y biet
a) (x+5) mu 2 + (2y - 8 ) mu 2 = 0
b)(x + 3).(2y - 1 ) = 5
a: \(\left(x+5\right)^2>=0\forall x\)
\(\left(2y-8\right)^2>=0\forall y\)
Do đó: \(\left(x+5\right)^2+\left(2y-8\right)^2>=0\forall x,y\)
Dấu '=' xảy ra khi \(\left\{{}\begin{matrix}x+5=0\\2y-8=0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x=-5\\y=4\end{matrix}\right.\)
b: \(\left(x+3\right)\left(2y-1\right)=5\)
=>\(\left(x+3\right)\left(2y-1\right)=1\cdot5=5\cdot1=\left(-1\right)\cdot\left(-5\right)=\left(-5\right)\cdot\left(-1\right)\)
=>\(\left(x+3;2y-1\right)\in\left\{\left(1;5\right);\left(5;1\right);\left(-1;-5\right);\left(-5;-1\right)\right\}\)
=>\(\left(x,y\right)\in\left\{\left(-2;3\right);\left(2;1\right);\left(-4;-2\right);\left(-8;0\right)\right\}\)
tim x thuoc N bieta, 125.n 5 7b, 2 3.n 3 4 2 5 5c, 2 3 2 n 3 2.n.5 10 10 2d, 5 n=
125
Tim x biet
a) x-2 trên 5 =3/8
b) x-1 trên x+5=6/7
c)x2 trên 6=24/25
a)x-2/5=3/8
(x-2).8=5.3
x-2=5.3:8
x-2=1
=>x=3
b,c )tương tự
5phan6:3phan8×3phan4=
\(\frac{5}{6}\div\frac{3}{8}\times\frac{3}{4}\)\(=\frac{5}{3}\)
\(\frac{5}{6}:\frac{3}{8}x\frac{3}{4}=\frac{5}{6}x\frac{8}{3}x\frac{3}{4}=\frac{5x8x3}{6x3x4}=\frac{5}{3}\)
\(\left(\frac{1}{4}+\frac{3}{8}\right)\times\frac{8}{7}\)
\(=\frac{5}{8}\times\frac{8}{7}\)
\(=\frac{5}{7}\)
#H
\(\left(\frac{1}{4}+\frac{3}{8}\right)\cdot\frac{8}{7}=\frac{5}{8}\cdot\frac{8}{7}=\frac{5}{7}\)
1/4 + 3/8 x 8/7
= ( 1/4 x 3/8 ) x 8/7
= 5/8 x 8/7
= 40/56 .
#Songminhtử
tren duong thang xy lay 3 diem phan bietA BC. Khi do
\(\frac{\sqrt{x}+1}{\sqrt{x}-2}+\frac{2\sqrt{x}}{\sqrt{x}+2}+\frac{2+5\sqrt{x}}{4-x}\)
a,rut gon
b,tim x de p duong
c,tim x de p = -5/2
d,tim x de p thuoc z
e,tim x de p >9/2
x^2 +(3a+2b)x-4 và x^2+(2a+3b)x+2b tim ab để 2 pt trên tương đương
1 tim GTLN của M=x2+y2+7/x^2+y^2+5
2 tim đa thức f(x) biết f(x-1)=x^2-3x+5
1) \(M=\frac{x^2+y^2+7}{x^2+y^2+5}=1+\frac{2}{x^2+y^2+5}\)
Ta có: \(x^2+y^2\ge0,\forall x;y\)
=> \(x^2+y^2+5\ge5\) với mọi x; y
=> \(\frac{2}{x^2+y^2+5}\le\frac{2}{5}\)
=> \(M\le1+\frac{2}{5}=\frac{7}{5}\)
Dấu "=" xảy ra <=> x = y = 0
Vậy max M = 7/5 đạt tại x = y = 0
2) \(f\left(x-1\right)=x^2-3x+5=x^2-x-2x+2+3\)
\(=x\left(x-1\right)-2\left(x-1\right)+3=x\left(x-1\right)-\left(x-1\right)-\left(x-1\right)+3\)
\(=\left(x-1\right)\left(x-1\right)-\left(x-1\right)+3\)
=> \(f\left(x\right)=x.x-x+3=x^2-x+3\)