Step-by-step explanation:
the easiest approach with a given point and the slope of the line is the point-slope form :
y - y1 = a(x - x1)
where "a" is the slope, and (x1, y1) is a point on the line.
so, we get
y - -8 = 4(x - -3)
y + 8 = 4(x + 3)
if we need the slope-intercept form
y = ax + b
we now simplify the point-slope form
y + 8 = 4x + 4×3 = 4x + 12
y = 4x + 4
Write the folowing in standard form and you well get
#1 is 5b
#2 is b−8x+<span>4</span>
(a-b) X (a+b)
= aXa - bXa +aXb -bXb (distributing)
Now, cross product of a vector with itself = 0
so, aXa = 0, bXb = 0
Also, aXb = - bXa
so,
(a-b) X (a+b) = 0 + aXb + aXb + 0
= 2aXb
hence, proved :)
