I need the answers for both a and b so thats why 61 points are up for grab

Step-by-step explanation:

From the picture attached,

a). Triangle in the figure is ΔBCF

b). Since, and are the parallel lines and m is a transversal line,

   m∠FBC = m∠BFG [Alternate interior angles]

   Since,   and are the parallel lines and n is a transversal line,

   m∠BCF = m∠CFE [Alternate interior angles]

   By triangle sum theorem in ΔBCF

   m∠FBC + m∠BCF + m∠BFC = 180°

   From the properties given above,

   m∠BFG + m∠CFE + m∠BFC = 180°

   m∠GFE = 180°

Therefore, angle GFE is the straight angle that will be useful in proving that the sum of the measures of the interior angles of the triangle is 180°.

a4 - 3a2 - 1

step-by-step explanation:

step   1   :

equation at the end of step   1   :

  ((a4) -   3a2) -   1

step   2   :

trying to factor by splitting the middle term

2.1     factoring   a4-3a2-1  

the first term is,   a4   its coefficient is   1 .

the middle term is,   -3a2   its coefficient is   -3 .

the last term, "the constant", is   -1  

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for