I must assume that you meant <span>X^2-10x =7. If that is indeed the case, then:
</span>X^2-10x =7 => x^2 -10x + 25 - 25 = 7, so that (x-5)^2 = 32 (Add 25, then
subtract 25)
Then x-5 = plus or minus sqrt(16)sqrt(2) = 4sqrt(2).
Then x = 5 plus or minus 4 sqrt(2) (answers)
Because the average is 7.7, his total points are equal to 7.7*10=77.
Because 7*10<77<8*10, Luke cannot have scored 8 10s. We now seek to prove that he can score 7 tens.
This leaves him with three tests left, that sum to 7 marks. There are clearly many ways to arrange this - for example, 2, 3, and 3 on the first three tests, then ten on all seven other tests. As this shows that 7 10s works and we have proven that 8 10s does not work, 7 is the maximum amount of 10s Luke could have scored.
Answer:
15
15
Step-by-step explanation:
x + 20 = 35
- 20 -20
x = 15
5x - 14 = 16 + 3x
+ 14 +14
5x = 30 + 3x
-3x - 3x
2x = 30
x = 15
Answer:
B) I can be little confident it might be close,or might be way off
