Answer:
Use by Prime factorisation method
Answer:
x = -2 ± sqrt(5)
Step-by-step explanation:
x^2 + 4x – 1= 0
Add 1 to each side
x^2 + 4x – 1+1= 0+1
x^2 +4x = 1
Take the coefficient of x
4
Divide by 2
4/2 =2
Square it
2^2=4
Add it to each side
x^2 +4x+4=1+4
(x+2)^2 = 5
Take the square root of each side
sqrt((x+2)^2 )=± sqrt(5)
x+2 = ± sqrt(5)
Subtract 2 from each side
x+2-2 = -2 ± sqrt(5)
x = -2 ± sqrt(5)
You add +7 to both sides and then divide by 9 to get the x alone.
Answer:
C. 60 ft
Step-by-step explanation:
If triangles ABC and EDC are in a 1:1 relation, they are congruent, and
AC = EC
5x - 5 = 3x + 9
5x = 3x + 14
2x = 14
x = 7
AC = 5x + 5 = 5(7) - 5 = 35 - 5 = 30 ft
EC = 3x + 9 = 3(7) + 9 = 21 + 9 = 30 ft
Distance between top and bottom of bridge = AC + EC = 30 + 30 = 60 ft
