Posted by ggift on Monday, September 14, 2009 at 10:36pm.
how did you get x=7 ?
4x - 18 = 65
add 18 to both sides
4x - 18 + 18 = 65 + 18
4x = 83
divide both sides by 4
x = 83/4 (not even anywhere close to 7)
i thought that it would be 7 because when i subtracted 18 from 65 i got 47 and 7 was missing from 4x
The interpretation of 4 and x in the expression "4x" as digits is used occasionally in mathematics, but more an exception than the rule.
In algebra, the multiplication sign is omitted when we multiply together two mathematical symbols or a number and a mathematical symbol.
xy is the same as x*y, and
4z equals 4*z.
It's the same principle as when we say 3 apples meaning 3 times the apples.
However, when we deal with two numbers, the multiplication sign is obligatory.
Oh, okay, thank you for explaining it to me.
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