The 1st, 4th, and 7th terms make an arithmetic sequence of their own. The 4th term is the average of the 1st and 7th, so ...
(1st +7th)/2 = 4th
1st + 7th = 2×4th
1st = 2×4th - 7th
The first term is ...
2*141 - 132 = 150
Answer:
Step-by-step explanation:
x²+6x = 18
coefficient of the x term: 6
divide it in half: 3
square it: 3²
add 3² to both sides to complete the square and keep the equation balanced:
x²+6x+3² = 18+3²
(x+3)² = 27
x+3 = ±√27 = ±3√3
x = -3±3√3
It equals -6 or -2 you do the two eqasions. x=-2-4 or x=2-4.
AAS they have a congruent side marked, the vertical angle and the marked congruent angle