Simplify : \[3x\left( 4x-5 \right)+3\]and find its value |
(a) \[x=3\] |
(b) \[x=\frac{1}{2}:\] |
Answer:
\[3x\left( 4x-5 \right)+3~\] \[=3x\left( 4x-5 \right)+3~\] \[=12{{x}^{2}}-15x+3\] (a) For x=3, \[=12{{\left( 3 \right)}^{2}}-15\left( 3 \right)+3\] \[=12\left( 9 \right)-45+3\] \[=108-45+3=66\] (b) For\[x=\frac{1}{2}\], \[=12{{\left( \frac{1}{2} \right)}^{2}}-15\left( \frac{1}{2} \right)+3\] \[=3-\frac{15}{2}+3\] \[=6-\frac{15}{2}\] \[=\frac{12-15}{2}=\frac{-3}{2}\]
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