Answer: y = 7.5
Step-by-step explanation:
Suppose that y varies directly with x
That is, y∝x
Convert y∝x to a full equation by introducing a constant k to the right hand side.
Therefore, y = kx
Given that y = 10 and x = 20
Substitute y and x in the equation above. We have;
10 = k(20)
10 = 20k
20k = 10
k = 10/20
k = 0.5
Since k = 0.5, the equation y = kx becomes y = 0.5x
Now, to find y if x = 15, substitute x in equation y = 0.5x
Therefore, y = 0.5(15)
y = 7.5
Answer:
Step 3 is not correct (should be , not
Step-by-step explanation:
The expression that we have to simplify is:
We proceed step-by-step, in order to find the mistake did by Cedric:
1) First, we factorize the 5 outside:
--> this step is correct
2) We add +16 and -16 inside the brackets:
--> this step is correct
3) We rewrite the term as the square of a bynomial, which is
, so the expression becomes
--> we notice that this step is wrong: in fact, Cedric wrote
, which is not correct.
4) Now we continue: we rewrite -16+3 as -13,
5) Finally, we multiply the 5 by the terms in the bracket: