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I can't work out the math problem in grade one.
1, a road was bombed. After the operator lights the fuse, he must run 400 meters away before the explosive explodes.

That is to say:

Run at least 400 meters.

Assuming that the fuse is at least x meters long, it can prove the safety of the operator.

The emergency situation is that the operator just ran 400 meters and the fuse of X meters blew.

The time to blow the fuse is the same as the time for the operator to run 400 meters.

Column equation: x/0.0 12=400/5.

The solution is x = 0.96m m.

So the fuse must be more than 0.96 meters to ensure the safety of the operator?

2, let 5-3x=0, and get x=5/3.

The result can be verified. If x=4 (greater than 5/3) is brought into the equation, the result will be negative, and if x= 1 (less than 5/3) is brought into the equation, the result will be positive. So get the result.

Results:

X & gt5/3, the value of algebraic expression 5-3x is negative.

When x=5/3, the value of algebraic expression 5-3x is 0.

When x< is 5/3, the value of algebraic expression 5-3x is positive.

Okay? solve