Помогите тест,2 3 4 5 задание

3. (у+5)^2–(у–5)(у+5)= у^2+10у+25–у^2+25=10у+50=–47+50=3 4. а) 4(5а–b)(5a+b) = 4(25a^2–b^2) = = 100a^2–4b^2 б) (c^4+d^3)^2=c^8+2c^4d^3+d^6 в) (х+6)^2–(х–6)^2=(х+6–х+6)(х+6+х–6)=12*2х=24х 5. а) (3х–2)^2 – (3х–1)(3х+1) = –2х 9х^2–12х+4–9х^2+1+2х=0 –10х+5=0 –10х=–5 х=1/2 б) 25а^2–81=0 (25а–9)(25а+9)=0 25а–9=0; 25а+9=0 25а=9. 25а=–9 а1=9/25. а2= –9/25