The 2th term of The A. P is 7 and 4th term is 28 Find The Common difference and The first term. help me please

d = 10.5, a₁ = - 3.5

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 a₂ = 7 and a₄ = 28 , then

a₁ + d = 7 → (1)

a₁ + 3d = 28 → (2)

Subtract (1) from (2) term by term to eliminate a₁

2d = 21 ( divide both sides by 2 )

d = 10.5 ← common difference

Substitute d = 10.5 into (1)

a₁ + 10.5 = 7 ( subtract 10.5 from both sides )

a₁ = - 3.5 ← first term

option c) graph of line going through 1, 4 and 3, 10

step-by-step explanation:

let y equal to margo's coin collection

let x equal to number of years

at the begining x=0, y=1 → point=(x,y)→point=(0,1)

she adds 3 coins per year, then y=1+3x

at x=1, y=1+3(1)=1+3→y=4→point=(x,y)→point=(1,4)

at x=3, y=1+3(3)=1+9→y=10→point=(x,y)→point=(3,10)

the graph of line going through (1, 4) and (3, 10), then the option c is the correct.

where's the diagram?

step-by-step explanation: