tìm GTNN
G= -3x^2+2x-1
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\(E=2x^2+8x+15\)
\(=\left(2x^2+8x+8\right)+7\)
\(=2\left(x^2+2.2.x+2^2\right)+7\)
\(=2\left(x+2\right)^2+7\)
\(2\left(x+2\right)^2\ge0\)
\(\Rightarrow2\left(x+2\right)^2+7\ge7\)
\(\Leftrightarrow Min_E=7\Leftrightarrow x+2=0\)
\(\Leftrightarrow x=-2\)
Vậy ...
\(4x^2-4xy+y-25a^2+10a-136\)
\(\text{Phân tích thành nhân tử}\)
\(-\left(4xy-y-4x^2+25a^2-10a+136\right)\)
k nhé !
Ta có :
\(x^8+x^7+1\)
\(=\left(x^8+x^7+x^6\right)-x^6+1\)
\(=x^6\left(x^2+x+1\right)-\left[\left(x^3\right)^2-1^2\right]\)
\(=x^6\left(x^2+x+1\right)-\left(x^3-1\right)\left(x^3+1\right)\)
\(=x^6\left(x^2+x+1\right)-\left(x^3+1\right)\left(x-1\right)\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left[x^6-\left(x^3+1\right)\left(x-1\right)\right]\)
\(=\left(x^2+x+1\right)\left[x^6-\left(x^4-x^3+x-1\right)\right]\)
\(=\left(x^2+x+1\right)\left(x^6-x^4+x^3-x+1\right)\)
\(x^2+y^2+z^2+2x-4y+6z=-14\)
\(x^2+y^2+z^2+2x-4y+6z+14=0\)
\(x^2+2x+1+y^2-4y+4+z^2+6z+9=0\)
\(\left(x+1\right)^2+\left(y-2\right)^2+\left(z+3\right)^2=0\)
\(\left(x+1\right)^2=0\) x+1 = 0 x = -1 | \(\left(y-2\right)^2=0\) y - 2 = 0 y = 2 | \(\left(z+3\right)^2=0\) z + 3 = 0 z = -3 |
vậy x + y + z = -1 + 2 + (-3) = -2
ồ, hay quá
(1/4)n = (1/2)2n = 1/22n = n = 1/2
cám ơn bn nhiu
a) x2-2x-y2+2y
=(x2-y2)-(2x-2y)
=(x-y)(x+y)-2(x-y)
=(x-y)(x+y-2)
\(G=-3x^2+2x-1=-3\left(x-\frac{1}{3}\right)^2-\frac{2}{3}\le-\frac{2}{3}\)
Vậy Min G = -2/3 <=> x = 1/3