Answer:
B if m=2
(Just to make sure that isn't m=-2, right?)
Step-by-step explanation:
7.8 + 2(0.75m + 0.4) = -6.4m + 4(0.5m - 0.8)
Let's plug in 2 for m.
7.8+2(0.75*2+0.4) = -6.4*2+4(0.5*2-0.8)
If 2 is a solution, then both sides will be the same.
If 2 is not a solution, then both sides will be different.
If both sides are the same, it is a true equation.
If both sides are different, it is a false equation.
Let's simplify 7.8+2(0.75*2+0.4)
According to PEMDAS, we must perform the operations in the parenthesis.
We have multiplication and addition in ( ). We will do the multiplication because the MD comes before the AS.
0.75*2=1.5
So now our expression 7.8+2(0.75*2+0.4) becomes 7.8+2(1.5+0.4)
Now to do the addition in the ( ).
1.5+0.4=1.9.
So now our expression 7.8+2(0.75*2+0.4) becomes 7.8+2(1.9).
We have multiplication to be perform now because again MD becomes before AS.
7.8+2(0.75*2+0.4) becomes 7.8+3.8
Last step perform the addition (the only operation left here on the left hand side)
7.8+2(0.75*2+0.4) becomes 11.6 .
Let's focus on the right now.
-6.4*2+4(0.5*2-0.8)
-6.4*2+4(1 -0.8) I did the multiplication in the ( ) first.
-6.4*2+4(.2) I did the subtracting in the ( ).
-12.8+.8 I did the multiplication by -6.4*2 and 4*.2 simultaneously
-12
I'm going to put all of this together because I think it might be easier to read:
7.8 + 2(0.75m + 0.4) = -6.4m + 4(0.5m - 0.8)
Plug in 2 for m
7.8 + 2(0.75*2 + 0.4)=-6.4*2 + 4(0.5*2 - 0.8)
7.8 + 2(1.5 + 0.4)= -6.4*2 + 4(1 -0.8)
7.8 + 2(1.9) = -6.4*2 + 4(.2)
7.8 + 3.8 = -12.8 +.8
11.6 =-12
This is false because 11.6 is not the same as -12.
m=2 leads to a false equation
B.
