Which is a quadratic function?

A, f(x) = 2x + x + 3
B, f(x) = 0x2 – 4x + 7
C, f(x) = 5x2 – 4x + 5
D, f(x) = 3x3 + 2x + 2

None

Step-by-step explanation:

A quadratic equation , is any equation that can be rearranged in standard form as : ax^2 + bx + c, where a and b and c are known numbers . I a =0 like all of the above examples, then the function or equation is linear.

for example : A,f(c) = 2x +x +3

= 3x +3 ===> equivalent to 0x^2 +3x +3

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15