SOLUTION: Please help me, This problem I have solved, but I have difficulty cheacked it. The problem was: Solve and cheack each of the following. 4 5 - = -, the answer that I got was x=

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Question 130752This question is from textbook algebra
: Please help me, This problem I have solved, but I have difficulty cheacked it.
The problem was: Solve and cheack each of the following.
4 5
- = -, the answer that I got was x=5.6
x 7
It is the right answer, but I dpn't know how to check it. Please help me, Thank You=) This question is from textbook algebra

Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
You have the correct answer. Good job!!!
.
To check your answer, just replace x by 5.6 in the original problem and show that both sides of
the equation are equal. For example, when you go to the original problem and replace x
by 5.6 the problem becomes:
.
4%2F5.6+=+5%2F7
.
There are several ways that you can check this problem.
.
First way ... use your calculator and divide 5.6 into 4. You should find that the answer to this
is 0.714285714. If you substitute this value into the problem in place of the entire left side
the problem becomes:
.
0.714285714=5%2F7
.
Now use your calculator to divide 7 into 5 ... and you will again get 0.714285714.
Substitute this value into the equation in place of the 5%2F7 on the right side and the
equation becomes:
.
0.714285714=0.714285714
.
Since both sides of the equation are equal to each other, the answer checks ... 4 divided by 5.6
is equal to 5 divided by 7. So x must equal 5.6
.
Second. You can always check proportions by cross multiplying. Multiply the numerator on
one side by the denominator on the other side. Do this for both numerators, and if the two
products are equal, the answer checks. So for this problem, multiply the numerator 4 by
the denominator on the other side (which is 7) and the product is 28. Then multiply the
numerator 5 by the denominator on the other side (5.6) and you also get a product of 28.
Since these two cross products are equal, the answer checks and 5.6 is correct.
.
Third way. Start with:
.
4%2F5.6+=+5%2F7
.
Notice that if you multiply the numerator 4 by 1.25 it the product is 5 ... making it the
same as the numerator on the other side. But if you multiply the numerator by 1.25 then
you must also multiply its denominator by 1.25. So multiply 5.6 times 1.25 and you get 7. So
by multiplying both the numerator and denominator on the left side by 1.25 you convert the
fraction on the left side to 5%2F7 and this is equal to the right side. In equation form this
is:
.
%284%2A1.25%29%2F%285.6%2A1.25%29+=+5%2F7
.
And this is equal to the right side. (Note that multiplying by 1.25%2F1.25 is the same
as multiplying by 1, so you are not changing the value of the original equation of 4%2F5.6.
.
Hope one of these ways will work for you in checking the problem.
.