Question

For the given equation, find the value of a,b, and c, determine the direction in which the parabola opens, and determine the y-intercept. Decide which table best illustrates these values for the equation: y= 7x^2 + 4x

Answer 1

Answer: Table C

a = 7; b = 4; c = 0; opens upward; y intercept at (0,0)

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Step-by-step explanation:

The given equation

y= 7x^2 + 4x

is the same as

y= 7x^2 + 4x + 0

Compare this to the template of y = ax^2+bx+c to find...

• a = 7
• b = 4
• c = 0

This points us directly to table C as the final answer

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If you wanted to keep going, then a > 0 means that the parabola opens upward. The 'a' is positive. To help remember this, think of "a is positive, so the parabola forms a positive happy smile".

In contrast, if 'a' was negative, then we'd have a negative frown for the parabola (it opens downward).

To find the y intercept, replace every x with 0 and compute y.

y = 7x^2+4x

y = 7(0)^2 + 4(0)

y = 0

The input x = 0 leads to the output y = 0

The y intercept is located at (0,0). This is also one of the x intercepts.