Current location - Training Enrollment Network - Mathematics courses - Ask some math questions: 1. It is proved that the straight line (3+2n)x+(4+n)y-2+2n=0 must pass through the second quadrant 2. Verification: straight lines x-y+ 1-2m=0 and 2x-y+ 1-3m=
Ask some math questions: 1. It is proved that the straight line (3+2n)x+(4+n)y-2+2n=0 must pass through the second quadrant 2. Verification: straight lines x-y+ 1-2m=0 and 2x-y+ 1-3m=
1, (2x+y+2)n+3x+4y-2=0 makes the value of this formula independent of n, that is, for any real number n, only 2x+y+2=0 and 3x+4y-2=0 are needed to get x =-2 and y = 2.

That is, the constant intersection point (-2,2) of a straight line is in the second quadrant, so it is proved.

2. Simultaneous equations can be used to solve x, y,

If the intersection is in the third quadrant, then the solution X.

3 、/question/92777895.html? fr=qrl&。 cid= 197。 Exponent = 3 & FR 2 = Query

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4. formula of barycenter coordinates: ((x 1+x2+x3)/3, (y 1+y2+y3)/3)

The coordinates of the center of gravity are (4/3, 2/3).

If the formula of the center of gravity is unknown, it can also be solved as follows:

The figure is a right triangle, and the center of gravity is the intersection of three midlines.

BC midpoint m, AM equation: y = 0.5x

Ac midpoint n (2,0), BN equation: y=-x+2.

Simultaneous am and bn equations, the intersection of solutions is the center of gravity.