Question

The value of the expression 2x² + x(100- 15 x) when x = 5 is X

a 119
b 129
c 135
d 145​

Answer 1

`\text{x}=5\\\\2\text{x}^2+\text{x}(100-15\text{x})=2\cdot5^2+5\cdot(100-15\cdot5)=\\\\=2\cdot25+5\cdot(100-75)=50+5\cdot25=\\\\=50+125=\boxed{175}`

Answer 2

`\boxed{ \boxed{ \mathrm{ \: \: \: \: \: \: \: \: \: 175 \: \: \: \: \: \: \: \: \: }}}`

Solution :

Plugging the value of x as 5 in the given expression we get,

`\hookrightarrow \: 2 {x}^(2) +x (100 - 15x)`

`\hookrightarrow \: 2(5) {}^(2) + 5(100 - (15 * 5))`

`\hookrightarrow \: (2 * 25) + 5(100 - 75)`

`\hookrightarrow \: 50 + 5(25)`

`\hookrightarrow \: 50 + 125`

`\hookrightarrow \: 175`