\(B=-3x^2+x+1\)
\(B=-3\left(x^2-\dfrac{1}{3}x-\dfrac{1}{3}\right)\)
\(B=-3\left[\left(x^2-2\cdot x\cdot\dfrac{1}{6}+\dfrac{1}{36}\right)-\dfrac{13}{36}\right]\)
\(B=-3\left(x-\dfrac{1}{6}\right)^2+\dfrac{13}{12}\)\(\le\dfrac{13}{12}\forall x\)
\(B=\dfrac{13}{12}\Leftrightarrow-3\left(x-\dfrac{1}{6}\right)^2=0\Leftrightarrow x=\dfrac{1}{6}\)
Vậy Max B = 13/12 <=> x = 1/6
Tim gia tri nho nhat:
36 - 3x+\(\dfrac{1}{2}\) \(x^2\)
bai 1
a = (3x / 2x + 4 ) + (x +3 /x ^ 2 - 4 )
a . tim x de gia tri phan thuc a duoc xac dinh
b. rut gon a
c. tinh gia trin cua a khi x bang -3
d . tim gia tri cua x de phan thuc co gia tri bang 2
Tim gia tri nho nhat :
P=(2x+1/x)2+(2y+1/y)2
cho hai so thuc x,y thoa man x^2+y^2=1. tim gia tri nho nhat cua p=x^6+y^6
\(\frac{143}{144}-\frac{1}{36x^2}-\frac{1}{36x}\) tinh gia tri lon nhat cua bieu thuc
cho bieu thuc A=[x+2/x^2-x+x-2/x^2+x].x^2-1/x^2+2
a) tim dieu kien cua x de gia tri cua bieu thuc A duoc xac dinh
b) tinh gia tri cua bieu thuc A voi x = -200
Xac dinh gia tri nho nhat cua bieu thuc: T=x^2+2xy+2y^2-2x-2y-2
tim gia tri cua m,biet rang 1 trong 2 phuong trinh sau day nhan x=-1 lam nghiem,phuong trinh con lai nhan x=5 lam nghiem : (1-x)(x^2+1)=0 va (2x^2+7)(8-mx)=0
tinh gia tri cua bieu thuc:
A=x^2+12x+36 tai x=64
B=x^2+4xy+4y^2 khi biet x=2,8; y=3,6
C=(3x-7)^2+10(3x-7)+25 biet x=16
D=8x^3-12x^2+6x-1 tai x=\(\dfrac{-1}{2}\)
