6. if z = -3, then what is z2 – 2 + 1?
7. if y= -5, then what is 3y2 + 7y -4?
8. if a = 6 and b = -2, what is (a-b)/(a+b)?
9. if m = 4 and n = 3, what is (m2 - n2)/ (m2 + n2)?
10. if x=4 and y= 12, what is 1/x + 1/y

Statements reasons 1. ab ? cd; ad ? bc 1. given 2. ac ? ac 2. reflexive property 3. ? adc ? ? cba 3. ? 4. ? dac ? ? bca; ? acd ? ? cab 4. cpctc 5. ? dac and ? bca are alt. int. ? s; ? acd and ? cab are alt. int. ? s 5. definition of alternate interior angles 6. ab ? cd; ad ? bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3?