Find the x intercepts of thr following parabola y= -4x^2 + 8x +12

x=-1 or x=3

Step-by-step explanation:

This is a quadratic equation

You can use the graph tool to visualize the x-intercepts on the graph as attached below.

x=-1 or x=3

For this case we must find the x-intersepts values of the following equation:

 

Doing y = 0 we have:

Dividing between -4 on both sides of the equation:

We factor, we look for two numbers that when multiplied by -3 and when added by -2. These are -3 and 1:

Thus, the x-intercepts values are:

42 = piano and/or guitar
26 = guitar
33 = piano
19 = piano and guitar

piano only = 33 - 19
= 14

guitar only = 26 - 19
= 7

total played = 19 + 14 + 7
= 40

Total musicians = 42
not played = 42 - 40
= 2

the answer for first column under the "piano"
play guitar = 19
Don't play guitar = 14
Total = 33

the answer for second column under the "Don't play piano"
play guitar = 7
Don't play guitar = 2
Total = 9

the answer for third column under the "Total"
play guitar = 26
Don't play guitar = 16
Total = 42