(1 + 2) x (3 + 4) whats the answer?

Which of the following is true for the relation f(x)=2x^2+1

Lin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. she knows that the total cost to download 3 videos was $12. her work to find the equation is shown below. joylin’s work step 1 k= 3/12= 0.25 step 2 y= 0.25x where did joylin make her first error?

Aquadratic equation in standard from is written ax^2= bx+c, where a,b and c are real numbers and a is not zero?