Question

Find the value of c such that the point (2, 5) lies on the graph of
f(x) = cx^2 + 4x − 2.

c=

Answer 1

All points are of the form (x,y)

So,

(x,y) = (2, 5)

which means

x = 2, y = 5

Answer 2

So the idea is that if you plug in x = 2, you should get y = 5 or f(x) = 5

Answer 3

f(x) = cx^2 + 4x − 2

f(x) = c(2)^2 + 4(2) − 2 ... plug in x = 2

5 = c(2)^2 + 4(2) − 2 ... plug in f(x) = 5

now solve for c

Answer 4

so c=2?

Answer 5

c = 2 is incorrect

Answer 6

would the answer be -5?

Answer 7

5 = c(2)^2 + 4(2) − 2

5 = c(4) + 4(2) − 2

5 = 4c + 8 - 2

5 = 4c + 6

c = ??

Answer 8

-1/4?

Answer 9

better

Answer 10

Thanks! people are very helpful