Question

Simplify 3x (4x – 5) + 3 and find its values for (i) x = 3 (ii) x = 12
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Answer 1

࿐Expression Given :

$:\mapsto\rm{3x (4x - 5) + 3}$

We have to simplify the Expression and then find the value of x .

1. By putting the value of x as 3
2. By putting the value of x as 12

✭Now let's Solve !

★Simplifying :

$:\leadsto\tt{3x (4x - 5) + 3}$

$:\leadsto\tt{3x\times4x - 3x \times5 + 3}$

$:\leadsto\tt{12x^2 - 15x + 3}$

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✴Step 1 :

Soluting by putting the value of x as 3

$:\implies\rm{12x^2 - 15x + 3}$

$:\implies\rm{12(3)^2- 15(3) + 3}$

$:\implies\rm{12(3\times3) - 15 × 3 + 3}$

$:\implies\rm{12\times9 - 45+3}$

$:\implies\rm{108-45+3}$

$:\implies\rm{108+3-45}$

$:\implies\rm{111-45}$

$:\implies\rm{66}$

✴Step 2 :

Soluting by putting the value of x as 12

$:\implies\rm{12x^2 - 15x + 3}$

$:\implies\rm{12(12)^2 - 15(12) + 3}$

$:\implies\rm{12(12\times12) - 15 \times12 + 3}$

$:\implies\rm{12\times144- 180+3}$

$:\implies\rm{1728-180+3}$

$:\implies\rm{1728+3-180}$

$:\implies\rm{1731-180}$

$:\implies\rm{1551}$

Thus ,

☆By putting the value of x as 3 the value of x we got is :

→$\blue{66}$

☆And,By putting the value of x as 12 the value of x we got is :

→$\blue{1551}$

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Answer 2

Question:

Simplify 3x (4x-5) + 3, and find its value for:

i) x = 3

ii) x = 12

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Solution:

First we will simplify the given expression.

3x (4x-5) + 3

$\implies \sf {12x^{2} - 15x + 3}$

$\implies \sf {12x^{2} - 15x + 3}$

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i) x = 3

Substitute the value of x as 3 in the simplified expression,

$\implies \sf {12x^{2} - 15x + 3}$

$\implies \sf {12 \times 3^{2} - 15 \times 3 + 3}$

$\implies \sf {12 \times 9 - 45 + 3}$

$\implies \sf {108 - 45 + 3}$

$\implies \sf {63 + 3}$

$\boxed {\bf {\red {66}}}$

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ii) x = 12

Substitute the value of x as 12 in the simplified expression,

$\implies \sf {12x^{2} - 15x + 3}$

$\implies \sf {12 \times 12^{2} - 15 \times 12 + 3}$

$\implies \sf {12 \times 144 - 180 + 3}$

$\implies \sf {1728 - 180 + 3}$

$\implies \sf {1548 + 3}$

$\boxed {\bf {\red {1551}}}$

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Final answer:

$\bigstar {\sf {\green {When\ x = 3,\ then\ the\ value\ is\ 66.}}}$

$\bigstar {\sf {\gray {When\ x = 12,\ then\ the\ value\ is\ 1,551.}}}$