First, we simplify 6x+2y=36 into 3x+y=18 by dividing by 2. This means that y=-3x+18.
The sum
can be written as:
,
<span>
from the binomial expansion formula: </span>
.
<span>
Thus, substituting </span>y=-3x+18 and simplifying we have<span>
</span>
.
This is a parabola which opens upwards (the coefficient of x^2 is positive), so its minimum is at the vertex. To find x, we apply the formula -b/2a. Substituting b=-108, a=10, we find that x is 108/20=5.4.
At x=5.4, the expression
, which is equivalent to
, takes it smallest value.
Substituting, we would find
=32.4 This is the smallest value of the expression.
For x=5.4, y=-3x+18=-3(5.4)+18=1.8.
Answer: (5.4, 1.8)
The unknown number is 69.
*If you reverse 69, it would be 96. Thus, increasing its value by 27.
96 - 69 = 27
*The sum of its digits 6 and 9 equals to 15.
-1/2( 3x -4) = 11
Use distributive properties:
-3/2 + 2,= 11
Subtract 2 from both sides:
-3/2x = 9
Divide both sides by -3/2
X = 9/ -3/2
X = -6
The answer is c. -6