Pls help extra points
1 answer:
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Answer:
a₁ = - 24
Step-by-step explanation:
The n th term of an AP is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given a₇ = 2a₅ , then
a₁ + 6d = 2(a₁ + 4d) = 2a₁ + 8d ( subtract 2a₁ + 8d from both sides )
- a₁ - 2d = 0 → (1)
The sum to n terms of an AP is
=
[ 2a₁ + (n - 1)d ]
Given = 84 , then
(2a₁ + 6d) = 84
3.5(2a₁ + 6d) = 84 ( divide both sides by 3.5 )
2a₁ + 6d = 24 → (2)
Thus we have 2 equations
- a₁ - 2d = 0 → (1)
2a₁ + 6d = 24 → (2)
Multiplying (1) by 3 and adding to (2) will eliminate d
- 3a₁ - 6d = 0 → (3)
Add (2) and (3) term by term to eliminate d
- a₁ = 24 ( multiply both sides by - 1 )
a₁ = - 24
Answer:
Option D. It's a perfect square trinomial.
Step-by-step explanation:
(a) 36x² - 4x + 16
= (6x)² - 2(2x) + (4)²
It's not a perfect square trinomial
(b) 16x² - 8x + 36
= (4x)² - 2x(4x) + (6)²
It's not a perfect square trinomial
(c) 25x² + 9x + 4
= (5x)² + 2 + (2)²
It's not a perfect square trinomial
(d) 4x² + 20x + 25
= (2x)² + 2(10x) + (5)²
= (2x+5)²
It's a perfect square trinomial.
Answer:
Step-by-step explanation:
Given
Required
Simplify the expression
Express the square root of 121 as 11
Express 90 as 9 * 10
Split the surd to 2
Express the square root of 9 as 3
Hence, the result of the expression is