Question

tim gia tri nho nhat cua bieu thuc

 A= (x-1)(x+2)(x+3)(x+6)

B=\(5x^2-4xy+y^2+4x+7\)

Answer 1

A=(x^2+5x-6)(x^+5x+6)=(x^2+5x)^2-36>=-36

A min=-36 <=> x(x+5)=0

<=>x=0;x=-5

B=(4x^2-4xy+y^2)+(x^2+4x+4)+3=(2x-y)^2+(x+2)^2+3>=3

B min=3 <=> x=-2;y=-4

tick mik nha