4. Mr. Sam plans to construct a trapezoidal shaped structure in his garden.
The longer side of trapezoid needs to start with a row of 96 bricks. Each
row must be decreased by 1 brick on each end and the construction
should stop at 23th row.
a) Find d.
[3 marks]
b) Show that the expression for the n'h row is 98-2n. Hence, state the
number of bricks in the 23th row.
[6 marks]
Answers
Answered by
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Answer for a) : d = -2
Step-by-step explanation:
because the question stated that each row must be decreased by 1 brick ON EACH END which the brick have two ends. right end and left end.
the arithmetic sequence would be : 96,94,92...
T1 = 96
T2= 94
d= T1 - T2 = 94 - 96= -2
Answer for b) : 52
Step-by-step explanation :
show the expression for the nth row is 98-2n
Tn = a+(n-1)d
a= 96 d= -2
= 96 + (n-1)(-2)
= 96 + (-2n) + 2
= 96 - 2n + 2
= 98 - 2n
number of bricks in the 23th row :
= 98 - 2(23)
=98 - 46
= 52
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