1.17 x²+ 3 x + 11x²=... 2.6pq+5p²-8pq-p²+pq=... 3.8+(a+2b)-12(2a-b)

1.
= 17x² + 3x + 11x²
= 28x² + 3x

2.
= 6pq + 5p² -8pq -p² + pq
= 5p² -p² + 6pq -8pq +pq
= 4p² + -pq

3.
= 8 (a + 2b) - 12 (2a -b)
= 8a + 16b -24a + 12b
= 8a -24a + 16b + 12b
= -16a + 28b