Choose all of the following equations that have a graph in which the parabola opens upward. More than one answer may be chosen.

A. y = 3x2 − 300
B. y = −25x2 − 4
C. y = x2 − 5x − 21
D. y = −x2 + 8x − 13

Question

Choose all of the following equations that have a graph in which the parabola opens upward. More than one answer may be chosen.
 	
A. y = 3x2 − 300
B. y = −25x2 − 4
C. y = x2 − 5x − 21
D. y = −x2 + 8x − 13

savvy · Answer

A and C because the coefficients of $$x^{2}$$ are positive in them.
A parabola opens upwards only if the coeff. of $$x^{2}$$ is positive.