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What is the equation, in standard form, of a parabola that contains the following points? (-2, 18), (0, 4), (4, 24)
y = 2x2 - 3x + 4
y = -3x2 + 2x + 4
y = -4x2 - 3x - 2
y = -2x2 + 3x - 4
Solution:
The standard form of the parabola is y = ax2 + bx + c
As it passess through (-2, 18), (0, 4), (4, 24), each of these points satisfies the equation of the parabola.
Substitute (-2, 18) in standard form of parabola, we get
18 = a (-2)2 + b (-2) + c
18 = 4a - 2b + c --- (1)
Substitute (0, 4) in standard form, we get
4 = c --- (2)
Substitute (4, 24) in standard form, we get
24 = a(4)2 + b(4) + c
24 = 16a + 4b + c --- (3)
Multiply equation (1) by 4
72 = 16a - 8b + 4c --- (4)
24 = 16a + 4b + c
Subtract both the equations (4) and (3)
48 = -12b + 3c
Substitute equation (2) c = 4, we get
48 = -12b + 3(4)
48 = -12b + 12
-12b = 48 - 12
-12b = 36
Divide both sides by -12
b = -3
Substitute the value of b = -3 in equation (1)
18 = 4a - 2(-3) + 4
18 = 4a + 6 + 4
4a = 18 - 6 - 4
4a = 8
Divide both sides by 4
a = 2
Therefore, the equation in standard form is y = 2x2 - 3x + 4.
What is the equation, in standard form, of a parabola that contains the following points? (-2, 18), (0, 4), (4, 24)
Summary:
The equation, in standard form, of a parabola that contains the following points (-2, 18), (0, 4), (4, 24) is y = 2x2 - 3x + 4.
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