Answer:
-12
Step-by-step explanation:
When you multiply a positive by a negative, the answer is always a negative. If you multiply two negatives, the answer is always positive. If you multiply 2 positives, the answer will always be positive.
 
        
             
        
        
        
Answer:  25x² - 64
<u>Step-by-step explanation:</u>
   (5x + 8)(5x - 8)
=        5x(5x - 8)   +    8(5x - 8)
=      25x² - 40x    +    40x - 64
=      25x²         + 0x           - 64
=              
NOTE: descending powers means the biggest exponent goes first, then the next biggest exponent, etc.
For example: x⁴ then x³ then x² then x then the number (which is actually x⁰)
 
        
             
        
        
        
Answer:
log(2)
Step-by-step explanation:
log(4) − log(2)
log(4/2)
log(2)
 
        
             
        
        
        
<u>Answer</u>
y = -2x + 10
<u>Explanation</u>
The general equation for a straight line is y = mx + c where m and c are gradient and y-intercept respectively. 
 y=x/2+3 = y (1/2)x + 3
gradient = 1/2
Gradient of the line perpendicular to y=x/2+3 is;
m × 1/2 = -1
m = -2 
Now we find the equation of a line passing through (1,8) and have a gradient of -2.
-2 = (y - 8)/(x - 1)
-2(x - 1) = (y - 8)
2 -2x = y - 8
y = -2x + 10