n - 7 = 21, n= 28 should be right bc the difference of 28 and 7 is 21
Answer:
Apparent Increase in Wave Frequency
As the ambulance approaches you, the distance between the source of the waves and the observer decreases. Consequently, the siren sounds more shrill as the pitch of the wailing siren 'sounds' higher than its original value, as sound waves reach you 'more frequently'.
Step-by-step explanation
hope this helps
Step-by-step explanation:
x²+2x-3=0
(x²+3x)-(x-3)=0
x(x+3)-1(x+3)=0
(x-1)(x+3)=0
x=1 or x=-3