Choose any of the animals (an elephant, a penguin, a dolphin, a tiger, a camel, a whale, a lion, a giraffe). Write an essay about it Use the plan:

а) x(x+3)-4(x-5)=7(x+4)-8
    x²+3x-4x+20=7x+28-8
    x²-x+20=7x+20
    x²-x-7x+20-20=0
    x²-8x=0
    x(x-8)=0
    х=0  или х-8=0
                   х=8
ответ: 0; 8
б) 2x^4-9x^2+4=0
    t=x²
    2t²-9t+4=0
    D=(-9)²-4*2*4=81-32=49=7²
    t1=(9+7)/4=4
    t2=(9-7)/4=1/2
x²=4                         x²=1/2
x1=2   x2=-2            x3=√1/2=√2/2    x4=-√1/2=-√2/2