the sum of the4thand8th terman apis24 andthe sumof the6thand10th termis44.find the first three term of the. ap
Answers
Step-by-step explanation:
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Answer:
Step-by-step explanation:
- Sum of fourth and eighth term is 24
- Sum of sixth and tenth term is 44
- First three terms of the A.P
→ The fourth term of an A.P is given by
a₄ = a₁ + (4 - 1)d
a₄ = a₁ + 3d---(1)
→ The eighth term of an A.P is given by
a₈ = a₁ + (8-1)d
a₈ = a₁ + 7d----(2)
→ By given we know that,
a₄ + a₈ = 24
→ Substitute the values from equation 1 and 2,
a₁ + 3d + a₁ + 7d = 24
2a₁ + 10d = 24
→ Divide the equation by 2
a₁ + 5d = 12--------(3)
→ Now in the second case,
→ The 6th term of an A.P is given by,
a₆ = a₁ + (6 - 1)d
a₆ = a₁ + 5d-----(4)
→ The 10th term of an A.P is given by
a₁₀ = a₁ + (10 - 1 )d
a₁₀ = a₁ + 9d----(5)
→ By given we know that,
a₆ + a₁₀ = 44
a₁ + 5d + a₁ + 9d = 44
2a₁ + 14d = 44
→ Divide the whole equation by 2,
a₁ + 7d = 22------(6)
→ Solve equation 3 and 6 by elimination method
a₁ + 7d = 22
a₁ + 5d = 12
2d = 10
d = 5
→ Hence common difference of the A.P is 5.
→ Substitute the value of d in equation 6
a₁ + 7 × 5 = 22
a₁ = 22 - 35
a₁ = -13
→ Hence the first term of the A.P is -13.
→ Second term of the A.P (a₂ ) = a₁ + d
Second term = -13 + 5
Second term = -8
→ Third term of the A.P is given by
Third term (a₃) = a₂ + d
Third term = -8 + 5 = -3
→ Hence the first three terms of the A.P is -13, -8, -3
→ a₄ +a₈ = 24
a₃ + d + a₁ + 7d = 24
-3 + 5 + -13 + 7 × 5 = 24
-11 + 35 = 24
24 = 24
→ a₆ + a₁₀ = 44
a₁ + 5d + a₁ + 9d = 44
-13 + 5 ×5 + -13 + 9 × 5 = 44
-13 + 25 + -13 + 45 = 44
12 + 32 = 44
44 = 44
→ Hence verified.