The graph represents the relation y = x 2 - 3x - 3. Find the
MATHEMATICS
WAEC 2011
The graph represents the relation y = x2 - 3x - 3. Find the value of x for which x2 - 3x = 7
- A. -1.55, 4.55
- B. 1.55, -4.55
- C. -1.55, -4.55
- D. 1.55, 4.55
Correct Answer: A. -1.55, 4.55
Explanation
x2 - 3x = 7
x2 - 3x - 7 = 0
What can you add to both sides of the equation to give the same value of y = x2 - 3x - 3
The number is 4
x2 - 3x - 7 + 4 = 4
x2 - 3x - 3 = 4
but y = x2 - 3x - 3
y = 4; So are y = 4 draw a line parallel to x axis, to cut or intersect the graph. At these points look down to see the corresponding values on x axis
This give -1.55 and 4.55
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