Problem 1 :
Evaluate using distributive property :
(i) 7(10 + 2)
(ii) 5(7 - 3)
(iii) 5(p + q)
(iv) m(n - p)
(v) 5(a2 + b2 + c2)
(vi) x(x2 - x)
Problem 2 :
Write the given verbal phrase into algebraic expression
(i) 3 times the sum of two different numbers
(ii) 7 times the difference of 5 times of a number and 4.
(iii) If 4 times the difference of a number and 5 is 32, find the number.
(iv) If 7 times the sum of 3 times of a number and 6 is 147, find the number.
Problem 1 :
Evaluate using distributive property :
(i) 7(10 + 2)
Solution :
Use distributive property.
= 7(10) + 7(2)
= 70 + 14
= 84
So, the value of 7(10 + 2) is 84.
(ii) 5(7 - 3)
Solution :
Use distributive property.
= 5(7) - 5(3)
= 35 - 15
= 20
So, the value of 5(7 - 3) is 20.
(iii) 5(p + q)
Solution :
Use distributive property.
= 5p + 5q
(iv) m(n - p)
Solution :
Use distributive property.
= mn - mp
(vi) 5(a2 + b2 + c2)
Solution :
Use distributive property.
= 5a2 + 5b2 + 5c2
(vii) x(x2 - x)
Solution :
Use distributive property.
= x ⋅ x2 - x ⋅ x
= x3 - x2
Problem 2 :
Write the given verbal phrase into algebraic expression
(i) 3 times the sum of two different numbers
Solution :
Let x and y be the two different numbers.
Then, 3 times the sum of two different numbers is
= 3(x + y)
Use distributive property.
= 3x + 3y
(ii) 7 times the difference of 5 times of a number and 4"
Solution :
Let x and y be the two different numbers.
Then, 7 times the difference of 5 times of a number and 4 is
= 7(7x - 5)
Use distributive property.
= 49x - 35
(iii) If 4 times the difference of a number and 5 is 32, find the number.
Solution :
Let x be the number.
Then,
4(x - 5) = 32
Use distributive property.
4x - 20 = 32
Add 20 to each side.
4x = 52
Divide each side by 4.
x = 13
So, the number is 13.
(iv) If 7 times the sum of 3 times of a number and 6 is 147, find the number.
Solution :
Let x be the number.
Then,
7(3x + 6) = 147
Use distributive property.
21x + 42 = 147
Subtract 42 from each side.
21x = 105
Divide each side by 21.
x = 5
So, the number is 5.
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