Which equation is a quadratic equation?

y + 3 = 5x + 10

y + 4x2 = (4x − 2)(x + 3)

y − 8x = (x2 + 1)(9x − 7)

y = 2x + 7x(x + 1)

Question

Which equation is a quadratic equation? 

y + 3 = 5x + 10 

y + 4x2 = (4x − 2)(x + 3) 

y − 8x = (x2 + 1)(9x − 7) 

y = 2x + 7x(x + 1)

anonymous · Answer

quadratic equation is equation with power of x as 2 , so here the option D

anonymous · Answer

y = 2x + 7x(x + 1)

anonymous · Answer

can u help with a few others ?

anonymous · Answer

yes sure

anonymous · Answer

What is the value of the coefficient "a" when the quadratic equation y = (3x − 4)(2x − 1) is written in standard form?
 
6 

5 

−11 

−4

anonymous · Answer

Can u write it in standard form by multiplying within the brackets

anonymous · Answer

y = 6x^2 -11x  + 4
So, a = 6

anonymous · Answer

Identify the vertex for the graph of y = 2x2 + 8x − 3. 

(2, 21) 

(2, 17) 

(−2, −11) 

(−2, −27)

anonymous · Answer

$$y=ax^2+bx+c$$ first coordinate of the vertex is $-\frac{b}{a}$
$$y=2x^2+8x-3$$ first coordinate of the vertex is $-\frac{8}{2\times 2}=-2$

anonymous · Answer

sorry i meant first coordinate of the vertex is 
$$-\frac{b}{2a}$$

anonymous · Answer

second coordinate of the vertex is what you get when you replace $x$ by the first coordinate

anonymous · Answer

@satellite73  so 2, -11 ?