Angle measures and segment lengths. Algebra Find the value of each variable.

An equation of the line tangent to y=x^3+3x^2+2 at its point of inflection is

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?

Find the sum of the given arithmetic series. 24 + 17 + 10 + 3 + + (–39)