SIgnificant digits

[maggie0160]

Can someone help me solve this I have tried everything in every method.

Solve for x, correct to 3 significant digits. 3.43x - 4.69(x + 1.06) = 5.78x.


I have gotten a few different answers, are any of them right?

x = -1.55
x = -1.21
x = -0.804
x = -0.706

 

[Unco]

You can check to see if you are correct by substituting your value for x back into the equation.

You've done well to arrive at four different solutions, though!

Just to make sure things are clear:

3.43x - 4.69(x + 1.06) = 5.78x

Expand the bracket:

3.42x - 4.69x + -4.69*1.06 = 5.78x

Simplify:
3.42x - 4.69x - 4.9714 = 5.78x

Add like terms:

-1.26x - 4.9714 = 5.78x

Move the x term on the left to right-hand side by addding:

-4.9714 = 7.04x

And divide through by 7.04 to get x=-0.706164772...

Consider the fourth digit, 1: The 6 does not need to be rounded up, so we have x = -0.706 (sf)

Well done on the fourth one, then!