Can someone please help me with this algebra
2 answers:
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Remember them is the best way to go.
draw the exact value triangles if you're unsure, but importantly, you just need to memorise these exact values.
draw the exact value triangles if you're unsure, but importantly, you just need to memorise these exact values.
Answer:
see explanation
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the initial value and d the common difference
Given
=
[ 10 + (n - 1)3 ]
Then by comparison
2a₁ = 10 ( divide both sides by 2 )
a₁ = 4 ← initial value
and d = 3 ← common difference
Thus
=
[ 10 + (7 × 3) ]
= 4(10 + 21)
= 4 × 31
= 124