help on 8th grade algebra

The Eighth(8th) grade Algebra mostly deals with Expressions and polynomials. An expression is a collection of variables, numbers, signs and operations according to given logic. Variables and constants are combined or grouped to make algebraic expressions or algebraic equation. A simple algebraic expressions like 4x + 4. Here 4x is the variable and a constant has a fixed value, It doesn’t change the value whenever

Solved problems on 8th grade algebra -
Find the value of (9x+4y)2, if x 2=1 , y2=2 and xy = 6.
Solution
x 2=1, y2=2, xy = 6.
Here using the identity of (x+y) 2=x2+2xy+y2
(9x+4y) 2
Here a=9x, b=4y, also using the identities of (a+b) 2=a2+2ab+b2
=(9x)2+2(9x)(4y)+(4y)2
=81x2+72xy+16y2 (from using the identity)
Now substitute x2=1,y2=2,xy=6
=81x2+72xy+16y2
=81(1) +72(6) +16(2)
=81+432+32
=545
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