X2 - 8x + 15 = 0
quadratic formula

The quadratic formula is x=(-b+-sqrt(b^2-4(a)(c)))/2a

Using the quadratic formula, we get:

x=(-(-8)+-sqrt((-8)^2-4(15)(1)))/2(1)

x=(8+-sqrt(64-60))/2

x=(8+-sqrt(4))/2

x=(8+-2)/2

x=10/2 and x=6/2

x=5 and x=3

We could do it way faster by completing the square:

x^2-8x+15=0

(x-5)(x-3)=0

x=5 and x=3

Hope both methods make sense! BTW, the +- thing means add or subtract

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.

step-by-step explanation:

it's is b