Question

using appropriate identities find the value of
(a) 10.3 x 10.4
(b)128^2-77^2
(c)(3x-4y) (2x-4y)

Answer 1

Answer:

System of Linear Equations entered :

[1] 2x + 3y = 91

[2] 3x + 4y = 128

Graphic Representation of the Equations :

3y + 2x = 91 4y + 3x = 128

Solve by Substitution :

// Solve equation [2] for the variable y

[2] 4y = -3x + 128

[2] y = -3x/4 + 32

// Plug this in for variable y in equation [1]

[1] 2x + 3•(-3x/4+32) = 91

[1] -x/4 = -5

[1] -x = -20

// Solve equation [1] for the variable x

[1] x = 20

// By now we know this much :

x = 20

y = -3x/4+32

// Use the x value to solve for y

y = -(3/4)(20)+32 = 17

Solution :

{x,y} = {20,17}

Terms and topics

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Linear equations with two unknowns

Solving linear equations by substitution

Related links

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Substitution to solve linear equations | Math Planet

Solving linear equations using substitution | for Dummies