You can study this guide.
Hi everyone,
i know i am way out of my league being on this forum but i am a mature student looking to get into college & for the corse i want i ned to repeat my maths exams! I tried signing up to a class but the pace was too fast for me. Anyway any help with this simple problem would be appreciated, thanks in advance!
Find the missing number in the following calculation:
-5x3x?=30
My question is this,
what is the formula or procedure to finding out the missing number, other examples are
(7?-5)x3=-9
or
?-(-3)x(-2)=-4
thanks again and i do apoligise for asking such a stupid question on here!
Laura
You can study this guide.
Traditionally in algebra, we represent the unknown quantity with a letter such as x or y, but any symbol will do, such as a question mark.
In the first example, we are given:
The associative and commutative properties of multiplication say that we may move/group factors as we choose, .i.e:
, etc.
So, we may write the equation as:
Now, compute the product within the parentheses:
Since the unknown quantity is being multiplied by -15, we want to divide both sides by -15 to isolate the unknown on its side of the equation. Whatever we do to one side of the equation we must also do to the other.
Now, we may cancel or divide out factors common to the numerators and denominators, and we are left with:
Second example:
Divide both sides by 3:
Now we want to add 5 to both sides to isolate the term with the unknown factor ( ):
Simplify:
Since the unknown is not separated by any characters, it is implied that we have the product .
Divide both sides by 7:
Third example:
Simplify by computing the product on the left side (a negative times a negative is positive, but this positive is being subtracted):
Add 6 to both sides:
Add like terms:
-5x3x?=30
In this question we find out the ? as:
?=30/(-5*3)
?=30/(-15)
?=-2
Now similarly, all the other questions of this category can be solved same:
(7?-5)x3=-9
(7?-5)=-9/3
(7?-5)=-3
(7?=-3+5
7?=2
?=2/7
Similarly,
?-(-3)x(-2)=-4
?-(-3)=-4/-2
?-(-3)=2
?=2/3
Thus you can see you can solve every question falling under this category is solved step by step & equalizing each term accordingly.