Answer:
x= -2-√11. or. x= -2 + √11
Step-by-step explanation:
solving quadratic equation by completing the square
x^2+4x-7=0
x^2+4x=7
x^2+4x + (4/2)^2=7 + (4/2)^2 ( adding (1/2 coefficient of x)^2 on both sides
x^2+4x + 4=7 + 4
x^2+4x + 4=11. factorize(x^2+4x + 4) into (x + 2)^2
(x + 2)^2=11
√(x + 2)^2= + - √11
x + 2 = + - √11
there are two different solution .
x + 2 = -√11. or x + 2 = + √11.
x= -2-√11. or. x= -2 + √11.
Answer:
okj
Step-by-step explanation:
Answer: the units digit has to be a 1 digit number not 2
Step-by-step explanation:
Answer:
1. 516 ppm; 2. 561 ppm
Step-by-step explanation:
1. CO₂ increase at old rate
Time = 2100 - 2010 = 90 years
Increase in CO₂ = 90 yr × (1.4 ppm/1 yr) = 126 ppm
CO₂ in 2010 = 390 + 126 = 516 ppm
At the old rate, the CO₂ concentration in 2100 will be 516 ppm.
2. CO₂ increase at new rate
Time = 2100 - 2010 = 90 years
Increase in CO₂ = 90 yr × (1.9 ppm/1 yr) = 171 ppm
CO₂ in 2010 = 390 + 171 = 561 ppm
At the new rate, the CO₂ concentration in 2100 will be 561 ppm.
Answer:
6
Step-by-step explanation:
If there was one man, he would have taken 15×4= 60 hours
To complete the job in 10 hours, 60÷10 = 6 men will be needed
