Question

AC=18дм,AB:BC=5:4,AB-? AB BC =5/4​

Answer 1

Объяснение:

5x+4x=18

9x=18

x=2

AB=5x=5*2=10

Answer 2

To find the length of segment AB, we can set up a proportion based on the ratio given (AB:BC = 5:4) and then solve for AB.

The given ratio is AB:BC = 5:4, which means that AB is 5 parts and BC is 4 parts.

Now, let's set up the proportion using this information:

AB/BC = 5/4

We also know that AC = 18 dm, which means that AC is equal to AB + BC:

AC = AB + BC

Now, we can substitute the values:

18 dm = AB + BC

Since we want to find AB, we can isolate AB on one side of the equation:

AB = 18 dm - BC

Now, we can use the proportion AB/BC = 5/4 to find BC:

AB/BC = 5/4

Cross-multiply:

4 * AB = 5 * BC

Now, isolate BC:

BC = (4 * AB)/5

Now, substitute this expression for BC back into the equation AC = AB + BC:

18 dm = AB + (4 * AB)/5

To clear the fraction, multiply both sides by 5:

90 dm = 5 * AB + 4 * AB

Combine like terms:

90 dm = 9 * AB

Now, isolate AB by dividing both sides by 9:

AB = 90 dm / 9

AB = 10 dm

So, the length of segment AB is 10 decimeters.