Solve 3x2+48x−12=0 by completing the square.

Step-by-step explanation:

3x²+48x-12=0

divide everithing by 3

x²+16x-4 =0

(a+b)² = a²+ 2ab+ b²

so a=1, 2ab=2*1*b=2b=16 =2*8 therefore b=8

(x+8)²-4 -64 = 0 (make sure you take away the b²=64)

(x+8)² = 68

√(x+8)² = √68

x+8 = ±2√17

x= -8±2√17

56

step-by-step explanation:

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.