Examples with solutions for Variables and Algebraic Expressions: Comparison to an existing expression

Exercise #1

Which of the following expressions are equivalent to the following:

9y+4x+35 9y+4x+35

a. 3y+2x+6y+30+7 3y+2x+6y+30+7

b. 5y+3x+4y+30+x+5 5y+3x+4y+30+x+5

c. 4x+30+9y+5 4x+30+9y+5

d. 3(3y+10)+5+22x 3(3y+10)+5+2\cdot2x

e. 5(8+x)x+3y3y5 5(8+x)-x+3y\cdot3y-5

f. 2x2+3(2y+10)+5+3y 2x\cdot2+3(2y+10)+5+3y

Video Solution

Step-by-Step Solution

Let's simplify each expression option and compare them with the original expression 9y+4x+35 9y + 4x + 35 :

a. 3y+2x+6y+30+7 3y + 2x + 6y + 30 + 7

  • Combine like terms:
    3y+6y=9y 3y + 6y = 9y and 2x 2x , 30+7=37 30 + 7 = 37 .
  • The expression becomes: 9y+2x+37 9y + 2x + 37 , which is not equivalent to the original.

b. 5y+3x+4y+30+x+5 5y + 3x + 4y + 30 + x + 5

  • Combine like terms:
    5y+4y=9y 5y + 4y = 9y , 3x+x=4x 3x + x = 4x , 30+5=35 30 + 5 = 35 .
  • The expression becomes: 9y+4x+35 9y + 4x + 35 , which matches the original expression.

c. 4x+30+9y+5 4x + 30 + 9y + 5

  • Rearrange and combine constants:
    4x+9y+(30+5=35) 4x + 9y + (30 + 5 = 35) .
  • The expression becomes: 9y+4x+35 9y + 4x + 35 , which matches the original expression.

d. 3(3y+10)+5+22x 3(3y + 10) + 5 + 2 \cdot 2x

  • Distribute and simplify:
    33y=9y 3 \cdot 3y = 9y , 310=30 3 \cdot 10 = 30 , 5 5 , 22x=4x 2 \cdot 2x = 4x .
  • The expression becomes: 9y+30+5+4x=9y+4x+35 9y + 30 + 5 + 4x = 9y + 4x + 35 , which matches the original expression.

e. 5(8+x)x+3y3y5 5(8 + x) - x + 3y \cdot 3y - 5

  • Distribute and simplify:
    58=40 5 \cdot 8 = 40 , 5x=5x 5 \cdot x = 5x , x -x , and 3y3y=9y2 3y \cdot 3y = 9y^2 .
  • The expression becomes: 40+5xx+9y25 40 + 5x - x + 9y^2 - 5.
  • Arrange: 4x+9y2+35 4x + 9y^2 + 35 , which does not match the original expression.

f. 2x2+3(2y+10)+5+3y 2x \cdot 2 + 3(2y + 10) + 5 + 3y

  • Distribute and simplify:
    2x2=4x 2x \cdot 2 = 4x , 32y=6y 3 \cdot 2y = 6y , 310=30 3 \cdot 10 = 30 , 5 5 , and 3y 3y .
  • The expression becomes: 4x+6y+3y+30+5 4x + 6y + 3y + 30 + 5 .
  • Combine like terms:
    6y+3y=9y 6y + 3y = 9y .
  • The expression simplifies to 9y+4x+35 9y + 4x + 35 , which matches the original expression.

Therefore, the expressions a, e do not match the original, while b, c, d, and f do, confirming these are equivalent to 9y+4x+35 9y + 4x + 35 .

The correct answer is b. c. d. f.

Answer

b. c. d. f.

Exercise #2

Which expressions are equal to the following:

9a+5n 9a+5n

a. 4(a+n)+5an 4(a+n)+5a\cdot n

b. 3(an)+6a+8n 3(a-n)+6a+8n

c. 20a7n11a+12n 20a-7n-11a+12n

d. 10an+6an 10a-n+6a-n

e. 9(a+n)4n2 9(a+n)-\frac{4n}{2}

f. 3(a+n)(n5)+24a3n23an+20n 3(a+n)(n-5)+24a-3n^2-3an+20n

Video Solution

Step-by-Step Solution

To solve this problem, we will simplify each expression given in options a through f, and compare each to the expression 9a+5n 9a + 5n .

  • a. 4(a+n)+5an 4(a+n)+5a\cdot n
    Expanding, we have:
    4a+4n+5an 4a + 4n + 5an .
    The presence of the term 5an 5an makes it different from 9a+5n 9a + 5n . Therefore, it is not equivalent.
  • b. 3(an)+6a+8n 3(a-n)+6a+8n
    Expanding, we have:
    3a3n+6a+8n 3a - 3n + 6a + 8n .
    Combining like terms, we get:
    (3a+6a)+(3n+8n)=9a+5n (3a + 6a) + (-3n + 8n) = 9a + 5n .
    This matches 9a+5n 9a + 5n .
  • c. 20a7n11a+12n 20a-7n-11a+12n
    Combining like terms, we have:
    (20a11a)+(7n+12n)=9a+5n (20a - 11a) + (-7n + 12n) = 9a + 5n .
    This also matches 9a+5n 9a + 5n .
  • d. 10an+6an 10a-n+6a-n
    Combining like terms, we have:
    (10a+6a)+(nn)=16a2n (10a + 6a) + (-n - n) = 16a - 2n .
    This is not equivalent to 9a+5n 9a + 5n .
  • e. 9(a+n)4n2 9(a+n)-\frac{4n}{2}
    Expanding and simplifying, we have:
    9a+9n2n=9a+7n 9a + 9n - 2n = 9a + 7n .
    This is not 9a+5n 9a + 5n .
  • f. 3(a+n)(n5)+24a3n23an+20n 3(a+n)(n-5)+24a-3n^2-3an+20n
    Expanding 3(a+n)(n5) 3(a+n)(n-5) , we have:
    3(an+n25a5n)=3an+3n215a15n 3(an + n^2 - 5a - 5n) = 3an + 3n^2 - 15a - 15n .
    The expression becomes:
    (3an+3n215a15n)+24a3n23an+20n (3an + 3n^2 - 15a - 15n) + 24a - 3n^2 - 3an + 20n .
    Combining like terms, we find:
    9a+5n 9a + 5n .
    This matches 9a+5n 9a + 5n .

Therefore, the expressions that are equal to 9a+5n 9a + 5n are options b, c, and f.

The correct answer choice is b, c, f.

Answer

b, c, f

Exercise #3

Which expressions represent the same value?

45+5a+3ab+27b 45+5a+3ab+27b

a. (5+3b)(a+9) (5+3b)(a+9)

b. 45+23a+413ab+(3a+27)b 45+\frac{2}{3}a+4\frac{1}{3}ab+(3a+27)b

c. 2ab+5(9+a)+ab+9a3ba1 2ab+5(9+a)+ab+\frac{9}{a}\cdot\frac{3ba}{1}

d. 45+8ab+27b 45+8ab+27b

Video Solution

Step-by-Step Solution

To solve this problem, we will simplify each given expression and compare the results to the initial expression 45+5a+3ab+27b 45 + 5a + 3ab + 27b .

Let's analyze each option:

  • Option a: (5+3b)(a+9)(5+3b)(a+9)
    Distribute: =5a+45+3ba+27b = 5a + 45 + 3ba + 27b
    Which rearranges to: 45+5a+3ab+27b 45 + 5a + 3ab + 27b
    This matches the original expression.
  • Option b: 45+23a+413ab+(3a+27)b45+\frac{2}{3}a+4\frac{1}{3}ab+(3a+27)b
    Simplify: =45+23a+133ab+3ab+27b = 45 + \frac{2}{3}a + \frac{13}{3}ab + 3ab + 27b
    The terms do not simplify to match the original expression 45+5a+3ab+27b 45 + 5a + 3ab + 27b .
  • Option c: 2ab+5(9+a)+ab+9a3ba12ab+5(9+a)+ab+\frac{9}{a}\cdot\frac{3ba}{1}
    Simplify: Complete multiplication and distribution: =2ab+45+5a+ab+27b = 2ab + 45 + 5a + ab + 27b
    Combine like terms: =45+5a+3ab+27b = 45 + 5a + 3ab + 27b
    This matches the original expression.
  • Option d: 45+8ab+27b45+8ab+27b
    This expression: =45+8ab+27b = 45 + 8ab + 27b
    Depends on the situation with bb, might match if conditions hold, but generally does not match unless specified.

After careful comparison, option a and c definitely represent the same value as the original expression, while option d depends on specific conditions regarding b b .

The correct answer is: a, c, d (d. depends on b).

Answer

a. c. d. (d. depends on b)

Exercise #4

Which expressions are equal to the following: 79x+34y2 \frac{7}{9}x+\frac{3}{4}y^2

a. 34y(y+x)+x36 \frac{3}{4}y(y+x)+\frac{x}{36}

b. 4772x+18xy2+58y2 \frac{47}{72}x+\frac{1}{8}xy^2+\frac{5}{8}y^2

c. 79(x+y)45y2 \frac{7}{9}(x+y)-\frac{4}{5}y^2

d. 29x+59y2+79xy+14y2 \frac{2}{9}x+\frac{5}{9}y^2+\frac{7}{9}xy+\frac{1}{4}y^2

e. (x+y)(19+34y)+23x34xy+19y (x+y)(\frac{1}{9}+\frac{3}{4}y)+\frac{2}{3}x-\frac{3}{4}xy+\frac{1}{9}y

f. 97y2+43x \frac{9}{7}y^2+\frac{4}{3}x

Video Solution

Answer

e