X^4-25x^5-x^2+25x identity the linear factors

What is x and y intercepts for y=x+7

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

The figure shows triangle def and line segment bc, which is parallel to ef: triangle def has a point b on side de and point c on side df. the line bc is parallel to the line ef. part a: is triangle def similar to triangle dbc? explain using what you know about triangle similarity. part b: which line segment on triangle dbc corresponds to line segment ef? explain your answer. part c: which angle on triangle dbc corresponds to angle f? explain your answer. asap