WAEC - Further Mathematics (2021 - No. 35)
Given that f: x --> x\(^2\) - x + 1 is defined on the Set Q = { x : 0 ≤ x < 20, x is a multiple of 5}. find the set of range of F.
{21, 91, 221}
{21, 91, 221, 381}
{1,21, 91, 221}
{1,21, 91, 221,381}
Explanation
multiples of 5 less than 20 = 5, 10 and 15
= [ 5, 10 and 15 ]x\(^2\) - x + 1
x\(^2\) - x + 1
when x = 5
5\(^2\) - 5 + 1; 25 - 5 + 1 --> 21
when x = 10
10\(^2\) - 10 + 1
100 - 9 = 91
when x = 15
15\(^2\) - 15 + 1
225 - 15 + 1 = 211
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