Now the products get bigger and you start working backwards. You'll multiply trinomials, spot the special products, then pull out a GCF and factor differences of squares, trinomials and perfect squares.
Also known as Class 10 maths — the same topics, whether your school calls it grade, class or year.
Which of the following is the correct factoring of x2+10x+21?
To factor x2+10x+21, we need two numbers that multiply to 21 and add to 10.For each option, extract the two numbers from the binomials and check both conditions.
Check each option:(x+3)(x+7): 3×7=21✓, 3+7=10✓→correct(x−3)(x+7): -3×7=-21✘, -3+7=4✘→wrong product and wrong sum(x−7)(x+3): -7×3=-21✘, -7+3=-4✘→wrong product and wrong sum(x−7)(x−3): -7×-3=21✓, -7+-3=-10✘→sum should be 10
Only 3 and 7 pass both checks:∙Product: 3×7=21✓∙Sum: 3+7=10✓