Zadanie 1b
Use the arithmetic-sequence sum to show that T1(n) = n2 + 2n.
Determine terms and finite totals of equally spaced sequences, use sigma notation, and interpret arithmetic models in context.
Tę umiejętność sprawdza 39 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Use the arithmetic-sequence sum to show that T1(n) = n2 + 2n.
Find the greatest possible value of Sn, to two decimal places.
The first three assemblies are shown. Write down t3.
Find t4.
Show that .
Rods are supplied in boxes of 50. Find the maximum number of tiers that can be built using 12 boxes.
A complete assembly uses a whole number of boxes with no rods left over. Find its smallest possible positive number of tiers.
Each rod is 12 cm long. Find the minimum number of rods needed for an assembly whose height exceeds 2.5 m. Ignore rod thickness.
Assume the sequence is arithmetic. (i) Find k. (ii) Hence or otherwise, find u3.
Find its 23rd term.
The sum of its first n terms is zero, where n is a positive integer. Find n.
An arithmetic sequence satisfies u8 = 15 and u5 + u13 = 40. Find its first term and common difference.
Show that 2p − q = a.
Show that p>2.
Suppose a=16 and s>0. List the first four terms of (i) the arithmetic sequence; (ii) the geometric sequence.
Suppose a=16 and s>0, and define un = An + ln Gn. (i) Show that u_n is arithmetic and find its common difference. (ii) Show that .
An arithmetic sequence satisfies u8 = 21 and S19 = 285. Find the positive integer k for which uk = 0.
Show that L(x) = 2x + 8 is admissible.
(i) Show that r=−c/m. (ii) For admissible L, show that L(x) = mx + 2m2/(m − 1). (iii) State the further excluded value of m.
Exactly three admissible L have integer r,m,c. One is L(x) = 3x + 9. Use the general expression to find the other two. For an admissible linear function, c = 2m2/(m − 1) and r = −c/m, with m ≠ 0, 1.
For an admissible cubic F: (i) express r2 − r1 in terms of a,b; (ii) use the sum and difference of the stationary abscissas to show that r1 = (3a2 − 3ab − 2b)/(6a); (iii) use this result to show that b=0 or a=−1/3.
Determine the two admissible cubic functions with b=0.
Now set a=−1/3. (i) Express r₁ in terms of b. (ii) Hence or otherwise find the exact pairs (b,c) making F admissible. Give each value as a rational expression involving a square root.
(i) Find S_5. (ii) Given S_6=90, find u_6.
Find u_1.
Hence or otherwise, express u_n in terms of n.
Hence prove that the areas R_1,R_2,… form an arithmetic sequence.
Find p and q.
Find the fifth term.
Find p and q.
Find the fifth term.
(i) Verify algebraically that C1(n) = n(n − 1) + 1. (ii) The count 421 occurs in this r=1 scheme. Determine its index n.
For r=17 the counts may be written C17(n) = 1 + 34 + 68 + ⋯ + 34(n − 1), with just 1 at n=1. Use an arithmetic-series sum to show that C17(n) = 17n(n − 1) + 1.
Using tables or another suitable method, find the smallest count greater than 1 that occurs in both the r=1 and r=17 schemes.
State u₁.
Given uₙ=−38, find n.
Find the common difference.
Now suppose the series is arithmetic with common difference d. (i) Show that p=3/4. (ii) Write d as a rational multiple of ln x. (iii) If the sum of its first n terms is , find n.
Show that S1(n) = n2.
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