Question

А)(2/5-2/7):2/7•2/5 б)(5/6-3/10):+3/10):(3/10+2/15)

Answer 1

(2/5-2/7):2/7*2/5
1)2/5-2/7=14-10/35=4/35
2)4/35:2/7=2/5
3)2/5*2/5=4/25

во втором (б) не понятно -  либо делить, либо отнять

Answer 2

Let's simplify the given expressions step by step:

A) (2/5 - 2/7) / (2/7 * 2/5)

First, find the common denominator for the fractions inside the parentheses:

2/5 = 14/35 2/7 = 10/35

Now, rewrite the expression:

(14/35 - 10/35) / (10/35 * 14/35)

Combine the fractions inside the first set of parentheses:

(4/35) / (140/1225)

Now, divide the two fractions by multiplying the first fraction by the reciprocal of the second fraction:

(4/35) * (1225/140)

Now, multiply the fractions:

(4/35) * (1225/140) = (4 * 1225) / (35 * 140)

Now, simplify the fraction:

(4900/4900) = 1

So, the value of expression A is 1.

B) (5/6 - 3/10) / (3/10 + 2/15)

First, find a common denominator for the fractions inside the parentheses:

5/6 and 3/10 do not have a common denominator, but you can make them have a common denominator by finding the least common multiple (LCM) of 6 and 10, which is 30.

Rewrite the fractions:

(25/30 - 9/30) / (9/10 + 4/30)

Now, simplify the fractions inside the parentheses:

(16/30) / (9/10 + 2/30)

Now, find a common denominator for the fractions inside the second set of parentheses:

(16/30) / (27/30 + 1/30)

Combine the fractions inside the second set of parentheses:

(16/30) / (28/30)

Now, divide the two fractions by multiplying the first fraction by the reciprocal of the second fraction:

(16/30) * (30/28)

Now, simplify the fraction:

(8/7)

So, the value of expression B is 8/7.