Andy Mann is building a garden fence out of planks. The planks are 10 cm wide to the nearest cm. He needs to make 69 m of fencing altogether, correct to the nearest metre. How many planks does he need to order to make sure he has enough to complete the fence?

2 tens \( \times 2 \) tens \( = \) \( 20 \times 20= \)

21. \( x^{2}=81 \)

Approximate the area under the graph of \( f(x)=0.03 x^{4}-1.21 x^{2}+64 \) over the interval \( [2,10] \) by dividing the interval into 4 subintervals. Use the left endpoint of each subinterval. The area under the graph of \( f(x)=0.03 x^{4}-1.21 x^{2}+64 \) over the interval \( [2,10] \) is approximately (Simplify your answer. Type an integer or a decimal.)

\( \left. \begin{array} { l } { f ( x ) = ( \cos x ) ^ { x } } \\ { [ \ln ( \cos x ) - x \tan x ] ( \cos x ) ^ { x } } \\ { x ( \cos x ) ^ { x - 1 } ( \ln \cos x ) ( - \sin x ) } \\ { ( \cos x ) ^ { x } ( \ln \cos x ) ( - \sin x ) } \\ { x ( \cos x ) ^ { x - 1 } } \end{array} \right. \)

© Watch Video rite an equivalent expression by distributing the \( "- \) " sign outside the parenth \( -(-3.5 s-7) \)