1st you have to know that in mathematiques the signs preceding any number are of paramount importance:
1) addition of 2 digits with different signs:
a) 8 - 3 = 5
b)-8 + 3 = -5 (if the negative sign is associated with largest digit, then the subtraction will be negative and vice versa
c) addition of 2 digits with both negative sign
- 5 - 8 = -13 .You jus add up both by keeping the negative sign
2) Multiplication: 2 digits with different signs:
a) (8) x (-3) = -24
b) (-8) x (3) = -24 so (-) x (+) or (+) x (-) is ALWAYS negative
3) Multiplication: 2 digits with SAME signs;
a) +8 x +3 = 24
b) (-8) x (-33) =24 so (-) x (-) or (+) x (+) is ALWAYS POSITIVE
4) what applies on multiplication applies also on division (same principle)
5) Now we come to parenthesis: When you have parenthesis, the sign preceding the parenthesis is also of paramount importance:
a) a positive sign preceding a parenthesis doesn't affect the consents if you remove these parenthesis: +(5 + 3y) = 5+3y or 2(5+3y) = 10+6y
b) a NEGATIVE sign preceding a parenthesis DOES affect the consents if you remove these parenthesis:
-2(4x -2y -3) ==> If you remove the parenthesis by multiplying by (-2), all signs inside will change: the (+) become ( -) and vice versa,. However mind you, if you have a negative
Now let's take your equation: -15 - ( - 8 ) = -15 +8, remember a negative sign preceding any parenthesis will change all signs inside if you REMOVE the parenthesis: some examples:
a) -15 + 10 -(4-32x -4y)
1st (-15 + 10) = -5 since the largest number is preceded by a NEGATIVE sign
so : -5 - (4-32x -4y) remove the parenthesis -5 -4 + 32x +4y
b) -(-5-8) -(+5+8) ==> -5-8 -5-8 = -10 - 16 => - 26
.
Answer:
-2(3) + 4x -4 =-14
-6 + 4x -4=-14
4x = -14 + 6 + 4
4x = -4
x=-1
To verify this...Input -1 into the original equation... You'd get -14
<span>The answer is
2/5</span><span> or </span>0.4<span> cups of flour are needed.
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The answer to that question is d 2/3
Assuming this is a cylinder, surface area (using the formula) = 2πrh+2π(r^2)
r = diameter/2 = 4
h = height = 9
surface area becomes
2π*4*9 + 2π(4^2)
= 326.73
