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#### Online Quiz (WorksheetABCD)

Questions Per Quiz = 2 4 6 8 10

### Grade 7 - Mathematics4.25 Finding the Formula (a+b)2 (Geometrical Proof)

#### Find the value of (a+b)2

Suppose AB = a units, BC = b units,
\ AC = AB + BC = (a + b) units
Af = Ag + GF = (a + b) units
Area of square ACDF = AC * AF = (a + b) * (a + b)
= (a + b)2 sq. units    ..........I
Area of square ACDF
= Area of square ABHG + Area of  rectangle  BCIH + Area of Square HIDE + Area of rectangle GHEF
= AB * AG + BH * BC + HI * HE + GH * GF
= a*a + a*b + b*b + a*b
= (a2 + 2ab + b2) sq. units    .........II
\ from I and II

(a + b)2  = (a2 + 2ab + b2)

Directions: Solve the following problems. Also write at least ten examples of your own.
 Q 1: (7x+3)2 = _____?49x2-42x+97x2+42x+949x2+42x+9 Q 2: (9x+5)2 = _____?9x2+90x+2581x2-90x+2581x2+90x+25 Q 3: (4x+3)2 = _____?16x2+24x+916x2-24x+94x2+24x+9 Q 4: (9x+15)2 = _____?9x2+270x+22581x2-270x+22581x2+270x+225 Question 5: This question is available to subscribers only! Question 6: This question is available to subscribers only!