x² + bx - 81
there are 2 formula that fit this equation :
>> x² - a² = (x+a)(x-a)
or
>> x² + 2ax² + a² = (x+a)(x+a)
because the last value of our equation is negative value therefore we have to use the first formula >> x² - a² = (x+a)(x-a)
step:
x² + bx - 81
x² + bx - 9²
because we have to follow the first formula x² - a² therefore bx = 0
x² + bx - 9²
bx = 0
b = 0
Answer:
x = 27
Step-by-step explanation:
39/26 = x /18
cross multiply
26x = (39)(18)
26x = 702
x = 27
Answer:
43.82 mph
266.67 feet
Step-by-step explanation:
Given :
S = √30fl
S = speed of car
f = drag Coefficient
l = Length of skid mark
If f = 0.8 ; l = 80 feets
s = √30fl
s = √(30*0.8*80)
s = √1920
s = 43.817
s = 43.82 mph
B.)
s = 80 mph
f = 0.8
s = √30fl
80 = √30*0.8*l
80 = √24l
Square both sides
80² = 24l
6400 = 24l
l = 6400/24
l = 266.67 feets
-3(x+5)=-9
-3x-15=-9
+15 +15
-3x=6
-1x=2
1x=-2
x=-2