Substitution, equivalent expressions and quadratic identities.

Answer: 1

1. (u−v)2=(u+v)2−4uv=152−4×56=1.

Answer: −22

1. The x coefficient gives 2+k−12=−3
2. k=7.
3. The constant is q=2×7−62=−22.

Answer: 170

1. Compare coefficients: p+q=18 and pq=77.
2. Then p2+q2=(p+q)2−2pq=170.