If a + b = y and a - b = z , then 3ab =
can someone explain!	Pick one:	A) (3y^2 - 3z^2)/4	B) (3z^2 - 3y^2)/4	C) 3y+3z/2	D) 3y - 3z/2	E) 3y^2 - 3z^2/2
plugging numbers is quite fast in this case:   Let   a=1   b=2   Then; y= 1+2= 
<gadget id="calculator">1+2</gadget>
<output>3</output>
&gt; 3 and z= 1-2=&gt; -1   Question asks 3ab=.........   As our number 3ab= 3*1*2= 
<gadget id="calculator">3*1*2</gadget>
<output>6</output>
6   now plug the value of y and z in the answer choices. Option A gives 6 and that is the number we need.   Hence: (3y^2 - 3z^2)/4ns is (3y^2 - 3z^2)/4.
<result>A</result>
If a + b = y and a - b = z , then 3ab =
can someone explain!