Given that binary quadratic form F(X)= 1/2xtax, and A=[1, 2; 2,4], the quadratic form is ().
A. positive definite
B. negative definite
C. indefinite
D. positive semidefinite
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From visual characteristic, the visual distance of instrument panel had better be 70CM or so, its height had better be level with eye photograph, when decorating, face plate should hind tilt () degree Angle.
A. 15
B. 30
C. 45
D. 60
The hesser matrix of F(X) with n variables is the n×n partial derivative matrix, so the matrix is ().
A. non-symmetric matrix
B. symmetric matrix
C. triangular matrix
D. partition matrix
n order to enable operators to move freely at work and avoid adverse psychological barriers and physical injuries, the minimum floor area of the workshop shall not be less than () m squared.
A. 80
B. 8
C. 0.8
D. 20
Given that F(X)=-2x12+2x1x2-x22+2x1, it is determined that its stagnation point (1,1) is ().
A. the smallest pointt
B. Minimum point
C. Maximum point
D. the biggest point