the average of the five number was 6.8. If the first four numbers were 4.3, 5.2, 7, and 6.8, What was the fifth number?
1 answer:
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Answer:
8 =
= 11.31
Step-by-step explanation:
let the two numbers be x and y
From the first sentence,
xy=24
x+y=10
Then make y in equation 2 the subject of the formular and substitute in equation 1
x+y=10
y=10-x
substituting in equation 2
x(10-x)=24
open the bracket
10x-x^2=24
=-x^2+10x=24
Transfer the constant to the left hand side
=-x^2+10x-24=0
Then factorise completely
Look at the photo above
