Помогите решить срочно!!!

1.
2cos²α-8sin²α=2(1-sin²α)-8sin²α=2-2sin²α-8sin²α=2-10sin²α
2-10*(0.3)²=2-10*0.09=2-0.9=1.1

2.
$7*20^{log_{20}3}-10log_{0.5} \frac{1}{4}= \\ =7*3-10log_{ \frac{1}{2} }( \frac{1}{2} )^2= \\ =21-10*2log_{ \frac{1}{2} } \frac{1}{2}= \\ =21-10*2=21-20=1$

3.
$( \frac{1}{5} )^{3-2x}- \frac{1}{625} \geq 0 \\ \\ ( \frac{1}{5} )^3*( \frac{1}{5} )^{-2x}- \frac{1}{125}* \frac{1}{5} \geq 0 \\ \\ \frac{1}{125}(( \frac{1}{5} )^{-2x}- \frac{1}{5} ) \geq 0 \\ \\ ( \frac{1}{5} )^{-2x}- \frac{1}{5} \geq 0 \\ \\ ( \frac{1}{5} )^{-2x} \geq (\frac{1}{5})^1 \\ \\ -2x \leq 1 \\ x \geq -0.5$
x∈[-0.5; +∞)