Factorise $7v-v^2$7v−v2.
Factorise $z^2+4z^4$z2+4z4.
Factorise $3x+xz-39y-13yz$3x+xz−39y−13yz.
Factorise $17rs+wr+17st+wt$17rs+wr+17st+wt.
solve quadratic equations including the use of the quadratic formula and completing the square