Examples with solutions for Square of sum: Using short multiplication formulas

Exercise #1

Write an algebraic expression for the area of the square below.

x+1x+1x+1

Video Solution

Step-by-Step Solution

To find the area of a square with side length x+1 x + 1 , we apply the formula for the area of a square, which is side squared. This means we need to calculate (x+1)2(x + 1)^2.

Here are the steps to solve the problem:

  • Step 1: Identify the expression for the side length. The side length of the square is given as x+1 x + 1 .
  • Step 2: Use the formula for the area of a square: (side)2(\text{side})^2.
  • Step 3: Substitute the side length with x+1 x + 1 : (x+1)2(x + 1)^2.
  • Step 4: Expand the expression using the formula for the square of a sum: (a+b)2=a2+2ab+b2(a + b)^2 = a^2 + 2ab + b^2, where a=x a = x and b=1 b = 1 .
  • Step 5: Calculation:
    • (x+1)2=x2+2(x)(1)+12(x + 1)^2 = x^2 + 2(x)(1) + 1^2
    • (x+1)2=x2+2x+1(x + 1)^2 = x^2 + 2x + 1

Therefore, the algebraic expression for the area of the square is x2+2x+1 x^2 + 2x + 1 .

Answer

x2+2x+1 x^2+2x+1

Exercise #2

The square below has an area of 36.

x>0 x>0

Calculate x.

363636x+1x+1x+1

Video Solution

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Set up the equation based on the given information. The side of the square is given by x+1 x + 1 , and the area formula for a square is (side)2(\text{side})^2. Thus, we set up the equation as (x+1)2=36(x + 1)^2 = 36.
  • Step 2: Solve for x x . Take the square root of both sides of the equation:

(x+1)=±36(x + 1) = \pm \sqrt{36}
(x+1)=±6(x + 1) = \pm 6

  • Since x>0 x > 0 is a condition, only the positive value of x+1 x + 1 is valid, so x+1=6 x + 1 = 6.
  • Solve for x x by subtracting 1 from both sides:

x=61x = 6 - 1
x=5x = 5

Therefore, the solution to the problem is x=5 x = 5 .

Answer

x=5 x=5