15 less than 4 times a number is 9 find the number
2 answers:
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Answer:
(1.13, 7.74) and (-4.13, 18.26)
Step-by-step explanation:
This can be solved in two ways: mathematically and graphically.
<u>Graphing</u>
Plot both lines and find where they intersect. See the attachment.
The intersection points are (1.13, 7.74) and (-4.13, 18.26)
<u>Mathematical</u>
y + 2x = 10
y = 10 - 2x
y = 3x² + 7x - 4
10 - 2x = 3x² + 7x - 4
3x² + 9x - 14 = 0
Solve this using the quadratic equation:
x = 1.13 and -4.13
Use these two values of x to find y:
y = 10 - 2x
y = 10 - 2(1.13)
y = 7.74
y = 10 -2x
y = 10 -2(-4.13)
y = 18.26
The two points are:
(1.13, 7.74) and (-4.13, 18.26)
