If the line with equation y=−2x+7 is rotated 90° clockwise about the origin, what are the coordinates of the image of its y-intercept? a. (0,−7) b. (−7,0) c. (2,0) d. (7,0)

First, find the y-intercept of the line y=-2x+7. When x=0 you have that y=-2·0+7, y=7, then point (0,7) is the y-intercept.

When you rotate this line 90° clockwise about the origin, then point (0,7) will be placed on the x-axis in positive x-direction. Rotation preserves the distances, then the coordinates of the image are (7,0).

correct choice is D.

solution:

→c= a b , that is product of a and b is possible only when when a is m × n matrix and b is n × p matrix.

that is, number of columns of a= number of rows of b.

so, size of matrix , c= a b is , if a = (m × n)matrix

b= (n × p)matrix

then a b = [ (m × n)matrix] ×[   (n × p)matrix ]

→→c= a b= [m × p ] matrix

→→size of product a b will be equal to = number of rows of a × number of columns of b

whats the