Question 137·200 Super-Hard SAT Math Questions·Advanced Math
If the quadratic equation above has exactly one real solution and , which choice is ? Anіko.аi - SАТ Рrep
When a quadratic involves parameters and you’re told it has exactly one real solution, immediately set the discriminant to 0 to get a clean relationship between the parameters (often a ratio). Then use the additional condition (here, ) to reduce to a single-variable equation, solve efficiently, and only at the end compute the exact expression the question asks for, including any absolute value. Property of Anіkο.aі
Hints
Discriminant idea
A quadratic has exactly one real solution when its discriminant equals 0.
Identify , , and
Match to , then compute .
Use the product condition
After you get a ratio between and , substitute into to get an equation in just one variable. Рreрarеd bу Аniкο.aі
Desmos Guide
Relate to using the product
Enter the relationship q=756/p (this encodes ).
Enter the discriminant-zero equation in terms of
From , substitute by entering:
49*(756/x)^2 = 144*x^2
Here x represents .
Find the -value(s) that satisfy it
Graph both sides by entering:
y=49*(756/x)^2
y=144*x^2
Find the intersection(s). The -coordinate(s) are possible values of .
Compute and match an option
For an intersection value , compute , then compute abs(p+q) (you can type it directly or use a small table). Choose the option that matches that value.
Step-by-step Explanation
Use the discriminant condition
For , exactly one real solution means the discriminant is 0:
Here , , and , so
Create an equation relating and
Simplify the discriminant equation:
Taking square roots gives
Combine with to find and
If , then . Substitute into :
So , and then (same sign as ).
(The case would make , which forces , contradicting .)
Compute
With and (or both negative),
Correct answer: 57