How do you solve and check your solution given #-3.4=0.4x#?

2 Answers
Jan 7, 2018

Answer:

#x = -8.5#
... see below :)

Explanation:

When it says to solve, it means to find what the unknown variable equals to. So you want to isolate x to find what x is.

#-3.4=0.4x#

#-3.4/0.4=(0.4x)/0.4#

#-8.5=x#

To check if what we got is correct, we can input the answer back into the equation. So since we found that x=-8.5, we want to replace x with -8.5

#-3.4=0.4x#

#-3.4=0.4(-8.5)#

#-3.4=-3.4#

The left side is equal to the right side, so therefore we know that our answer is correct.

Jan 7, 2018

Answer:

Find a value for #x# and then substitute it back into the original equation to see if it is true.

Explanation:

We are told #-3.4 = 0.4x#

Therefore, to begin, we need find a value for #x#. To do this we simply divide by the coefficient in front of #x# , in this case #0.4#

#therefore# #(-3.4/0.4) = x#

#therefore x =-17/2#

To check we substitute the values of #x# back into the original equation to see if it is true.

Subbing #-17/2# we get #-3.4 = 0.4(-17/2)#

which # -3.4 = -3.4 #